Biomedical subjects

J Kastrup

Publications and source records attributed to J Kastrup.

At least 19 recordsLinked to original sources

PubMed1996

Effects of orthotopic cardiac transplantation on structural microangiopathy and abnormal hemodynamics in idiopathic dilated cardiomyopathy.

To examine whether cardiac transplantation would reverse morphologic and hemodynamic changes in peripheral circulation in idiopathic dilated cardiomyopathy, the structure of terminal arterioles and minimal vascular resistance were measured in skin at the dorsum of the foot in the same 14 patients before and 80 +/- 21 (mean +/- SD) days and 387 +/- 46 days after transplantation. The results were compared with data from a group of 16 healthy subjects. Blood flow was measured by the local technetium-99m pertechnetate washout method in a vascular bed relaxed with histamine. Structural microangiopathy (enhanced thickening of the basement membranes) in the arterioles was disclosed in skin biopsies in 11 of 14 patients before transplant, but in none of the 16 control subjects (p < 0.002). These abnormalities were unchanged 80 days after cardiac transplantation. However, arteriolar wall thickening was significantly reduced over the 1-year period after transplantation (p < 0.05), but this was not complete. Transplantation also led to a significant delayed decrease in minimal vascular resistance: before transplantation, 10.1 +/- 3.2 mm Hg.ml-1.100 g.min (mean +/- SD); 80 days after transplantation, 9.3 +/- 3.1 mm Hg.ml-1.100 g.min (p = NS), and 1 year after transplantation 7.6 +/- 2.4 mm Hg.ml-1 100 g.min (p < 0.01). Minimal vascular resistance before and 80 days after transplantation was significantly increased compared with that in healthy control subjects (6.3 +/- 1.7 mm Hg.ml-1 100g.min [p < 0.0003 and p < 0.003, respectively]). However, 1 year after transplantation, minimal vascular resistance was reduced to comparable levels when compared with that in control subjects (p = NS). These results indicate that structural microangiopathy and minimal vascular resistance in skin are improved slowly and gradually within the first year after orthotopic cardiac transplantation in patients with idiopathic dilated cardiomyopathy, however, the remodeling of histopathology is not accompanied by complete normalization.

Adult↗

PubMed1995

Insulin-resistant glucose metabolism in patients with microvascular angina--syndrome X.

Studies in patients with microvascular angina (MA) or the cardiologic syndrome X have shown a hyperinsulinemic response to an oral glucose challenge, suggesting insulin resistance and a role for increased serum insulin in coronary microvascular dysfunction. The aim of the present study was to examine whether patients with MA are insulin-resistant. Nine patients with MA and seven control subjects were studied. All were sedentary and glucose-tolerant. Coronary arteriography was normal in all participants, and exercise-induced coronary ischemia was demonstrated in all MA patients. A euglycemic, hyperinsulinemic clamp was performed in combination with indirect calorimetry. Biopsy of vastus lateralis muscle was taken in the basal state and after 4 hours of euglycemia and hyperinsulinemia (2 mU.kg-1.min-1). The fasting level of "true" serum insulin was significantly higher (43 +/- 6 v 22 +/- 3 pmol/L, P < .02) and the rate of insulin-stimulated glucose disposal to peripheral tissues was lower in patients with MA (13.4 +/- 1.0 v 18.2 +/- 1.4 mg.kg fat-free mass [FFM]-1.min-1, P < .02) due to a decrease in nonoxidative glucose metabolism (8.4 +/- 0.9 v 12.5 +/- 1.3 mg.kg FFM-1.min-1, P < .02). No difference was found in glucose or lipid oxidation rates between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Nocturnal temperature and subcutaneous blood flow in humans.

The aim of this study was to investigate the possible relationship between variations in local skin and body temperatures, and a subcutaneous hyperaemia response during sleep in humans. Nocturnal subcutaneous blood flow (SBF) was measured in the lower legs of 9 subjects for 8-12 h under outpatient conditions. The core temperature was measured by a tympanic membrane temperature sensor, and the local skin temperature was measured by a skin temperature sensor. The 133Xe wash-out technique with portable CdTe(Cl) detectors was used for measurement of the SBF. The SBF increased significantly (P < 0.0001) after 1 h sleep, with the hyperaemia persisting for 2 h. During the hyperaemic phase, the local skin temperature increased significantly (P < 0.0001) and then decreased again in the post-hyperaemic phase (P < 0.01). The core temperature decreased significantly during the measurement period (P < 0.01). Separate ordinary linear regression analyses revealed no significant correlations between the measured temperature parameters and the blood flow levels during sleep. The results indicate no governing role of the local skin or body temperatures on the local SBF. The local skin temperature increased significantly secondary to the nocturnal subcutaneous hyperaemia (i.e. active vasodilatation), which is believed to be involved in a thermoregulatory effector mechanism.

Adult↗

PubMed1995

Microvascular distensibility in two different vascular beds in idiopathic dilated cardiomyopathy.

The local isotope-washout technique allows discrimination between blood flow in skin and muscle. Arteriolar constriction, mediated by the sympathetic nervous system, is abolished in a papaverine-histamine-relaxed vascular bed. Microvascular distensibility of relaxed resistance vessels was measured in skeletal muscle and skin of the lower limb in patients with congestive heart failure (CHF) secondary to idiopathic dilated cardiomyopathy and in healthy subjects. Vascular transmural pressure was elevated 40 mmHg by head-up tilt and caused muscle blood flow to increase by 11 +/- 9% in 20 CHF patients compared with 44 +/- 20% in 11 control subjects (P < 0.0003). Also the increase in skin blood flow was significantly reduced: 31 +/- 18% in 42 CHF patients compared with 62 +/- 29% in 25 control subjects (P < 0.001). Regression analysis demonstrated a significant association between microvascular distensibility in skin and skeletal muscle tissue (P = 0.003, r = 0.51, n = 31). Structure of terminal arterioles was determined in skin biopsies, and structural microangiopathy was found in 32 of 42 CHF patients. Multiple regression analysis demonstrated the degree of microangiopathy to be the only parameter significantly associated with microvascular distensibility (P = 0.005, r = 0.42). (There was no association to NY Heart Association functional class, left ventricular ejection fraction, duration of CHF, age of subject, or mean arterial blood pressure.) We conclude that patients with idiopathic dilated cardiomyopathy have similar decreased microvascular distensibility in skeletal muscle and skin. Furthermore, structural alterations in terminal arterioles seem to be associated with decreased distensibility and increased stiffness of the cutaneous microvascular bed.

Adult↗

PubMed1994

Altered peripheral vasodilator profile of nitroglycerin during long-term infusion of N-acetylcysteine.

OBJECTIVES: The aim of this study was to compare the short- and long-term effects of intravenous nitroglycerin plus placebo and nitroglycerin plus N-acetylcysteine on peripheral arteries, veins and microcirculation in humans. BACKGROUND: The thiol donor N-acetylcysteine may potentiate the hemodynamic response to nitrates in nitrate-tolerant and nontolerant patients. The vascular changes responsible for this effect are not clear. METHODS: Eight male volunteers were treated with nitroglycerin (0.1 microgram/kg per min) combined with N-acetylcysteine (2 g intravenously, followed by 5 mg/kg per h) or placebo for 23 h in a double-blind, randomized, crossover study. Venous volume, the diameter of the radial and temporal arteries, calf blood flow and subcutaneous blood flow were measured at baseline and repeated after 1 and 23 h of infusion. RESULTS: Prolonged coadministration of N-acetylcysteine and nitroglycerin potentiated the acute venodilator effect of nitroglycerin as estimated by changes in venous volume (nitroglycerin plus N-acetylcysteine, 4.45 +/- 0.36 ml/100 g; nitroglycerin plus placebo, 3.65 +/- 0.46 ml/100 g, mean +/- SEM, p < 0.05) and prevented development of tolerance as seen after 23 h of treatment with nitroglycerin plus placebo (4.35 +/- 0.25 vs. 3.47 +/- 0.41 ml/100 g, p < 0.05). N-acetylcysteine had no effect on nitroglycerin-induced changes in arterial diameters (p > 0.05) but significantly increased microcirculatory subcutaneous blood flow after 1 h (nitroglycerin plus N-acetylcysteine: 6.3 +/- 1.3 ml/100 g per min vs. nitroglycerin plus placebo: 3.5 +/- 0.3 ml/100 g per min, p < 0.05) and after 23 h (4.4 +/- 0.6 vs. 3.1 +/- 0.5 ml/100 g per min, p < 0.05). CONCLUSIONS: The results suggest that coadministration of nitroglycerin and N-acetylcysteine in humans 1) potentiates and preserves nitroglycerin-induced venodilation and 2) augments the effect of nitroglycerin on small resistance vessels (regulating subcutaneous blood flow) without affecting the response to nitroglycerin in middle-sized arteries. Both the development of nitrate tolerance and the administration of N-acetylcysteine significantly change the normal vasodilator profile of nitroglycerin in humans.

Acetylcysteine↗

PubMed1994

Orthotopic cardiac transplantation reverses abnormal reflex regulation of the microvasculature in the lower leg.

OBJECTIVE: The aim was to investigate the effect of cardiac transplantation on reflex control of lower leg subcutaneous blood flow. METHODS: The reflex regulation of subcutaneous blood flow of the lower leg was studied in 11 patients following orthotopic cardiac transplantation, in 11 patients with severe congestive heart failure (New York Heart Association functional class III or IV), and in 11 healthy subjects. Four patients were studied before and after cardiac transplantation. Cause of heart failure was classified as idiopathic dilated cardiomyopathy in all heart failure patients and in all the cardiac transplant patients before transplantation. Blood flow was measured by the local 133xenon washout method in the supine position and during 45 degrees head up tilt. RESULTS: When performing head up tilt without activation of the local nervous venoarteriolar axon reflex in patients with congestive heart failure, the relative subcutaneous blood flow increased abnormally, by 50(SD 25)%, but in patients after cardiac transplantation a normal decrease was seen [-28(13)%, p < 0.001]. The responses in the transplant group were similar to those observed in normal controls with a decrease in blood flow [-32(15)%; NS]. Head up tilt with simultaneous activation of the local venoarteriolar axon reflex increased blood flow [31(22)%] in patients with heart failure as compared to the decrease in blood flow found in the transplants [-44(17)%, p < 0.001]. The decrease of blood flow was not significantly different between the transplant group and control subjects [-53(19)%; NS]. CONCLUSIONS: These results indicate that abnormal reflex regulation in severe congestive heart failure with peripheral vasodilation of the lower leg during orthostasis is reversed and even normalised after cardiac transplantation. The haemodynamic consequence may be a regaining of an oedema-protective mechanism that eliminates the stress (capillary hypertension) on the microcirculation seen in severe heart failure.

Adult↗

PubMed1994

Short- and long-term survival after aortic balloon valvuloplasty for calcified aortic stenosis in 137 elderly patients.

UNLABELLED: Percutaneous transluminal balloon aortic valvuloplasty was performed in 137 patients with symptomatic severe calcified aortic stenosis (50 men and 87 women, mean age 77 years) between December 1986 and September 1990. The purpose of the study was to evaluate short- and long-term survival after balloon aortic valvuloplasty, mean follow-up was 19 months. At the time of balloon aortic valvuloplasty congestive heart failure (NYHA III-IV) was present in 89%, angina pectoris in 47%, and syncope in 31% of the patients. Aortic balloon dilatation produced significant decreases in peak pressure gradient from 91 +/- 34 mmHg to 40 +/- 26 mmHg (p < 0.001). The procedure related mortality was 8% (11 pts) and the 30-days mortality 17% (23 pts). Severe complications occurred in 25% of the patients during the procedure and within the first 24 hours. Immediate clinical improvement was noted in 68% of the patients surviving the treatment. The overall survival rate was at one, two, three and four years follow-up 63%, 40%, 28%, and 21%, respectively. These survival rates were all statistically different from the survival rates in an age- and sex-matched background population (p < 0.001). A multivariate Cox analysis revealed that only female sex and angina before treatment seemed to improve survival. CONCLUSION: The long-term outcome after aortic balloon valvuloplasty for severe aortic stenosis is so poor that we recommend aortic valve replacement as the initial treatment in these patients, if at all possible.

Adult↗

PubMed1993

Lack of effect of peripheral nervous blockade on nocturnal fluctuations in lower-leg subcutaneous blood flow in man.

1. The local subcutaneous adipose tissue blood flow was measured simultaneously in the right and left lower legs of 10 normal human subjects under out-patient nocturnal conditions. The 133Xe-wash-out technique, portable CdTe(Cl) detectors and a portable data-storage unit were used for the measurement of blood flow. 2. The purpose of the study was to unveil the possible role of centrally controlled nerve fibres to the measurement area as mediators of a previously described nocturnal subcutaneous hyperaemia of 2 h duration. Therefore, before the sleeping period, a local nervous blockade was applied immediately proximal to the isotope depot on the right lower leg by the injection of approximately 15 ml of bupivacaine (5 mg/ml) subcutaneously. 3. Control experiments revealed blockade of the baroreceptor vasoconstrictor reflex activity 4 h after application of the local nervous blockade in three subjects examined. 4. Identical nocturnal isotope-wash-out curves were recorded from the two legs. Subcutaneous blood flow was found to increase significantly (P < 0.0001) after approximately 1 h of sleep and the hyperaemia persisted for 2 h. 5. A significant positive correlation was detected between the latency periods from going to bed until the onset of the hyperaemia in the right and left lower legs (P < 0.001, r = 0.95). 6. No significant difference could be detected between the relative blood flow increase during the hyperaemic phase in the right and left lower legs (P = 0.83). 7. It is concluded that the present data seem to rule out a central nervous factor(s) as the eliciting mechanism of the nocturnal subcutaneous hyperaemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMed1993

Abnormal baroreceptor-mediated vasodilation of the peripheral circulation in congestive heart failure secondary to idiopathic dilated cardiomyopathy.

BACKGROUND: Peripheral edema is a major clinical problem in congestive heart failure (CHF). The function of the edema-protective baroreceptor-mediated and local nervous vasoconstrictor reflexes of the lower leg during orthostasis in moderate and severe CHF has largely been unexplored. METHODS AND RESULTS: Baroreceptor-mediated and local nervous regulation of subcutaneous blood flow of the lower leg was studied in healthy subjects and in patients with moderate and severe CHF secondary to idiopathic dilated cardiomyopathy. Blood flow was measured by the local 133Xe washout method in the supine position and during 45 degrees head-up tilt. When the central baroreceptor reflex alone was activated, the changes in subcutaneous blood flow of the heart failure patients in both groups were significantly different from those of the eleven control subjects: blood flow increased 48 +/- 26% in 10 severe and 3 +/- 24% in nine moderate CHF patients compared with the decrease in blood flow of -36 +/- 15% observed in 11 control subjects (p < 0.0001 for both). A highly significant direct association was demonstrated between changes in blood flow and New York Heart Association functional class (p = 0.007) and the left ventricular ejection fraction (p = 0.01). Activation of the baroreceptor and local venoarteriolar axon reflexes simultaneously increased blood flow significantly (30 +/- 9%) in 14 patients with severe CHF, compared with the decrease found in 14 control subjects (-53 +/- 9%) and in the group of 14 patients with moderate CHF (-17 +/- 25%) (p < 0.0001 for both). CONCLUSIONS: Patients with CHF secondary to idiopathic dilated cardiomyopathy have an abnormal baroreceptor-mediated vasodilation in subcutaneous tissue of the lower leg during the upright position, which increases with the severity of the disease. The hemodynamic consequence is capillary hypertension and hyperemia in the leg during the upright position that may contribute to the development of edema and to the initiation of structural changes (microangiopathy) demonstrated in the microcirculation.

Adult↗

PubMed1993

Diurnal blood pressure profile in patients with severe congestive heart failure: dippers and non-dippers.

Patients with severe congestive heart failure (CHF) have increased sympathetic nervous activity and altered baroreceptor function, which may influence the diurnal blood pressure rhythm. The 24-h blood pressure profile was measured in 25 patients with severe CHF (mean ejection fraction: 17%) and 25 control subjects. Systemic blood pressure was measured automatically at the arm by a non-invasive blood pressure monitoring system every 15 min. The mean +/- SD systolic blood pressure in CHF patients and controls was during day-time 105 +/- 10 and 130 +/- 11 mm Hg and night-time 97 +/- 10 and 112 +/- 10 mm Hg, i.e. the nocturnal decrease was 9 +/- 6 and 18 +/- 8 mm Hg, respectively (p < 0.0005 for all). The subjects could be divided into two groups: dippers and non-dippers, with and without a relative decrease in nocturnal systolic blood pressure > 10%. There was significantly more non-dipping CHF patients (16) than controls (5) (p < 0.01). Systolic blood pressure was in CHF dippers vs. non-dippers during day-time: 108 +/- 7 vs. 104 +/- 12 mm Hg (NS) and night-time: 92 +/- 7 vs. 99 +/- 11 mm Hg (p = 0.08). The nocturnal decrease was 16 +/- 3 vs. 5 +/- 4 mm Hg and the relative nocturnal decrease 15 +/- 3 vs. 5 +/- 3% (p < 0.00001 for both). It is concluded that patients with severe congestive heart failure can be divided into two groups: dippers and non-dippers, with and without a normal decrease in nocturnal blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Evidence of increased microvascular resistance and arteriolar hyalinosis in skin in congestive heart failure secondary to idiopathic dilated cardiomyopathy.

Does nervous microvascular stress from backward cardiac failure and abnormal baroreceptor-mediated vasodilation in the upright position alter the microvascular resistance and structure of the resistance vessels with time? The minimal vascular resistance and structure of the terminal arterioles were measured in skin at the dorsum of the foot in 14 healthy subjects, in 12 patients with short-term congestive heart failure (CHF) (New York Heart Association functional class greater than or equal to II for less than 1 year), and in 14 with long-term CHF (New York Heart Association functional class greater than or equal to II for greater than 1 year). Blood flow was measured by the local technetium-99m-pertechnetate washout method in a vascular bed paralyzed by histamine before, during and after 3 to 5 stepwise increases of external counter pressure. Minimal vascular resistance was calculated from the relation between blood flow and applied pressure. Minimal vascular resistance was significantly increased in both short-term (9.0 +/- 1.9 mm Hg.ml-1.100 g.min; p = 0.0003) and long-term (9.1 +/- 3.6 mm Hg.ml-1.100 g.min; p = 0.008) CHF patients compared with that in healthy control subjects (6.0 +/- 1.7 mm Hg.ml-1.100 g.min). Structural microangiopathy (increased hyalinosis of the basement membranes in the terminal arterioles) was found in skin biopsies in 21 of 24 patients with CHF in whom biopsies were obtained, but in none of the 14 control subjects (p less than 0.002). Multiple regression analysis demonstrated a weak but significant direct association between minimal vascular resistance and the degree of structural microangiopathy (p less than 0.03; r = 0.45).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1992

Nocturnal variations in lower-leg subcutaneous blood flow in paraplegic men.

1. Lower-leg subcutaneous adipose tissue blood flow rates were measured over 12-20 h under ambulatory conditions by means of the 133Xe-washout technique in nine paraplegic men, all with complete spinal cord lesions at or below the Th 6 level, and in nine age-matched healthy men. Portable CdTe(Cl) detectors and data-storage units were used. 2. The central and local sympathetic vasoconstrictive activity at the lower leg was measured under laboratory conditions by means of the 133Xe-washout technique and a stationary NaI(Tl) detector system. 3. The paraplegic men were found to have intact central and local sympathetic vasoconstrictive activity in their lower legs. Moreover, they all had a nocturnal hyperaemic blood flow phase of the same magnitude and duration as the control subjects. 4. The possibility that the somaesthetic nerves play a role in the hyperaemic response could be excluded, as all the paraplegic men suffered from complete lower-leg somaesthetic denervation. 5. A significant correlation was found between the time of going to bed and the nightly hyperaemic response in the right and left lower legs (P less than 0.01). 6. It is concluded that the present data are in accordance with the concept of a central nervous or humoral elicitation of nocturnal hyperaemia, although local metabolic and other factors might participate as well. Paraplegic men have an intact regulation of the postural and nocturnal changes in peripheral blood flow whether of central sympathetic or humoral origin.

Adipose Tissue↗

PubMed1992

Nocturnal variations in human lower leg subcutaneous blood flow related to sleep stages.

Nocturnal subcutaneous adipose tissue blood flow rate was measured in the lower legs of 10 normal human subjects together with systemic arterial blood pressure, heart rate, and registration of sleep stages under ambulatory conditions. The 133Xe washout technique, portable CdTe(Cl) detectors, and a portable data storage unit were used for measurement of blood flow rates. The sleep recordings were performed with a portable computerized sleep analysis system. In accordance with the results of previous studies, a hyperemic blood flow rate phase (mean increase 140%) for 100 min was observed approximately 60 min after the subjects went to bed. The moment of onset of the hyperemic phase was closely related to the moment of onset of the first episode of deep sleep (stages 3 and 4). There was a significant (P < 0.01) overrepresentation of deep sleep in the hyperemic phase compared with adjacent phases, and rapid-eye-movement sleep predominantly occurred in the latter part of the night, when the subcutaneous blood flow rate was stable. The results of the present study are in accordance with current theories of the interrelationship between the thermoregulatory and the arousal state control systems and, thus, might suggest that the nightly subcutaneous hyperemia represents a thermoregulatory effector mechanism.

Adipose Tissue↗

PubMed1991

Diurnal variations in lower leg subcutaneous blood flow rate in patients with chronic venous leg ulcers.

The blood flow rate in subcutaneous adipose tissue was measured on the lower legs of 11 patients with chronic lower-leg venous insufficiency and ulceration and in eight age-matched control subjects for 12-20 h, under ambulatory conditions, using the 133Xe wash-out technique with portable Cadmium telluride (CdTe(Cl)) detectors. In both groups, the change from an upright to a supine position at the beginning of the night period elicited an instantaneous increment in the blood flow rate of 30-40% with a decrease in the central and local postural sympathetic vasoconstrictor activity. After approximately 1 h of sleep, a considerable increase in blood flow rate was seen in both patient and control groups which persisted for nearly 100 min. In the patient group, the mean increase was 137% compared to a mean increase of 68% in the control group (P less than 0.01). The blood flow then returned to the same level as at the beginning of the night and remained stable until the subjects woke in the morning. The differences between this nocturnal hyperaemic phase and the adjacent phases were highly significant in both groups (P less than 0.0001 and P less than 0.005, respectively). The blood flow levels measured on the second day were of the same magnitude as those registered on the first day. The mean values of the wash-out rate constants (k) of the two groups were of the same magnitude in all phases of subcutaneous blood flow level, except in the hyperaemic phase, where it was significantly higher in the patient group (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1991

Ambulatory measurement of nocturnal fluctuations in subcutaneous blood flow rate in the lower leg of man during 12-h periods with the portable CdTe(Cl) detector. Methodological considerations.

Possible sources of error during long-term measurements of subcutaneous blood flow rate with the portable CdTe(Cl) detector system were ruled out in the present study. Local blood flow rates were recorded in the lower legs of normal human subjects by means of the 133Xe wash-out technique. A good correlation was found between the portable CdTe(Cl) and stationary NaI(Tl) detector systems both prior to (r = 0.88, P less than 0.0001) and after (r = 0.68, P = 0.07) day over night (12 h) measurements. Identical post-ischaemic reactive hyperaemia could be demonstrated by both detector systems 12 h after the application of the isotope depot. This indicates that blood flow rates and vascular reactivity can be measured over 12 h by the portable CdTe(Cl) detector. Identical results were obtained during the 12-h measurements performed with the portable CdTe(Cl) detector attached directly to the skin surface and with the detector elevated above the skin surface. Therefore, geometrical changes were without any influence on our measurements. We conclude that measurements of subcutaneous blood flow rates in the lower leg of human subjects can be performed under out-patients conditions by means of the 133Xe wash-out technique and portable CdTe(Cl) detectors. A skin area greater than or equal to 4 cm should be labelled by means of the atraumatic, epicutaneous labelling technique and the detector attached directly to the skin surface with a single layer of a 20-micron thick gas-tight Mylar membrane interposed between the skin surface and the detector. The investigation of the subcutaneous blood flow rate should not be initiated until at least 90 min after labelling.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Regional variations in nocturnal fluctuations in subcutaneous blood flow rate in the lower leg of man.

The purpose of the study was to investigate possible regional variations in recently discovered nocturnal fluctuations in subcutaneous blood flow rates. Approximately 90 min after going to sleep, a 100% blood flow rate increment, lasting about 100 min, has been demonstrated in the distal and medial aspect of the right lower leg of normal human subjects. In the present study subcutaneous adipose tissue blood flow rates were measured simultaneously in the right and left lower legs of 16 normal human subjects over 12-20 h ambulatory conditions. The 133Xe wash-out technique, portable CdTe(Cl) detectors and a portable data storage unit were used. The tracer depots were applied on the medial aspects of the right lower leg and on the medial (series 1) and lateral (series 2) aspect of the left lower leg 10 cm proximal to the malleolar level by means of the epicutaneous, atraumatic labelling technique. A nocturnal hyperaemic response was demonstrated at both the medial and lateral aspect of the leg. As for the degree of hyperaemia and the absolute blood flow rates in the different phases, there were some deviations between the medial and the lateral locations. However, a highly significant positive correlation was observed in both series concerning the duration of the period from going to bed until the hyperaemia phase (P less than 0.001). The mechanisms involved in the nightly subcutaneous hyperaemia are at present unknown. The sudden, synchronized increase in nocturnal subcutaneous blood flow points to a central nervous or humoral elicitation, although local metabolic factors might participate as well.

Adult↗

PubMed1991

Vibratory and thermal thresholds in diabetics with and without clinical neuropathy.

Vibration and thermal detection threshold and heat pain threshold were determined in 34 diabetics scrutinized for clinical neuropathy using a standardized questionnaire and examination form. On the basis of the clinical grading patients were classified as having either no neuropathy or a neuropathy of increasing severity. As expected thermal and vibratory detection threshold increased with increasing severity of neuropathy. Comparison between diabetics without symptoms and signs of neuropathy and a corresponding non-diabetic control group showed that a warm sensibility index (WSI = the range in which non-noxious heat is perceived) was significantly lower on feet in diabetics than in their matched non-diabetic controls. The findings show that quantitative assessment of thermal sensitivity may be of value to detect early small nerve fiber dysfunction even in patients without symptoms or signs of a clinical neuropathy.

Adult↗

PubMed1991

Nocturnal variations in subcutaneous blood flow rate in lower leg of normal human subjects.

Subcutaneous adipose tissue blood flow rate was measured in the lower leg of 22 normal human subjects over 12- to 20-h ambulatory conditions. The 133Xe washout technique, portable CdTe(Cl) detectors, and a portable data storage unit were used. The tracer depot was applied on the medial aspect of the right lower leg 10 cm proximal to the malleolar level by means of the epicutaneous, atraumatic labeling technique. The change from upright to supine position from day 1 in the beginning of the night period elicited an instantaneous blood flow rate increment of 30-40% in accordance with a decrease in central and local postural sympathetic vasoconstrictor activity. During sleep, characteristic variations in subcutaneous blood flow were disclosed. The 133Xe washout curve could be divided into three segments with significantly different slopes. Approximately 90 min after the subject went to sleep, an additional blood flow rate increment of considerable magnitude was observed. The mean increase was 84%, but in several cases a greater than 200% increment was measured (maximum 244%). The intra-individual coefficient of variation for the nocturnal blood flow response was in triplicate measurements 25% (n = 9). The hyperemic phase lasted approximately 100 min after which the blood flow rate returned to the level measured at the beginning of the night period. The blood flow rates measured on the second day did not differ from those on the first day. Control measurements performed under similar thermal conditions, but with the subjects kept awake, did not reveal any hyperemic phases. This points toward changes in cardiovascular regulatory mechanisms during sleep.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗