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Biomedical subjects

G Grassi

Publications and source records attributed to G Grassi.

At least 199 records · Page 11Linked to original sources
PubMed1987

Calcium antagonists and neural control of circulation in essential hypertension.

Data from animals and from man suggest that calcium antagonists interfere with alpha-adrenergic receptors and that this mechanism may be responsible for some of the vasodilation induced by these drugs. However, alpha-adrenergic receptors play a primary role in baroreceptor regulation of the cardiovascular system and blood pressure homeostasis, which might therefore be adversely affected by calcium antagonist treatment. We addressed this question in 14 essential hypertensives studied before treatment, 1 h after 20 mg oral nitrendipine and 5-7 days after daily administration of 20 mg oral nitrendipine. Blood pressure was measured by an intra-arterial catheter, heart rate by an electrocardiogram, cardiac output by thermodilution and forearm blood flow by venous occlusion plethysmography. Total peripheral and forearm vascular resistances were calculated by dividing mean blood pressure by blood flow values. Plasma norepinephrine was also measured (high performance liquid chromatography) in blood taken from the right atrium. Compared with the pretreatment values, acute nitrendipine administration caused a fall in resting blood pressure, an increase in the resting heart rate and cardiac output, and a fall in resting peripheral and forearm vascular resistance. The resting hypotension and vasodilation were also evident during the prolonged nitrendipine administration, which was, however, accompanied by much less resting cardiac stimulation than that observed in the acute condition. Baroreceptor control of the heart rate (vasoactive drug method) was similar before and after acute and prolonged nitrendipine treatment. This was also the case for carotid baroreceptor control of blood pressure (neck chamber technique) and for control of forearm vascular resistance as exerted by receptors in the cardiopulmonary region (lower-body negative-pressure and passive leg-raising techniques).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Alerting reaction and rise in blood pressure during measurement by physician and nurse.

Blood pressure was monitored by a continuous intra-arterial recording in 46 subjects to investigate whether the alarm reaction and the blood pressure and heart rate increases that occur during cuff blood pressure measurement made by a physician 1) attenuate when the physician's visit is repeated several times and 2) are less pronounced if a nurse measures the blood pressure. In 16 subjects the peak mean blood pressure and heart rate rises that occurred in the early part of the physician's first visit (22.6 +/- 1.8 mm Hg and 17.7 +/- 1.7 beats/min) were virtually identical to those occurring during three subsequent visits by the same physician throughout a 2-day intra-arterial blood pressure monitoring. The less pronounced pressor and tachycardic responses observed in the last part of the physician's visit also were virtually identical among the four visits. In contrast, in 30 other subjects the blood pressure and heart rate rises that occurred during the nurse's visit were 46.7% and 42.1% less (p less than 0.01) than those occurring during the physician's visit. The late and less pronounced pressor and tachycardic responses to the visit were also significantly less (p less than 0.01) in the former than in the latter condition. These results indicate that the error of overestimation of blood pressure inherent in cuff blood pressure measurement by a physician cannot be avoided by repeated visits by the physician over a short time span. It clearly can be reduced, however, if blood pressure measurements are performed by a nurse.

Emotions↗
PubMed1987

Hemodynamic effects of acute and prolonged administration of nitrendipine in essential hypertension.

In six hospitalized subjects with mild or moderate and untreated essential hypertension, we measured mean blood pressure (MBP, brachial artery catheter), heart rate (HR, electrocardiogram), cardiac output (CO, thermodilution), and total peripheral resistance (TPR, MBP divided by CO) at rest and during a cold pressor test (CPT, 60 s), a hand-grip exercise (HG, 40% maximum strength for 90 s), and a cyclette exercise (CE, 50 W for 5 min). The study was performed in a no-drug condition, 1 h after 20 mg oral nitrendipine (aN) and 1 week after daily administration of 20 mg oral nitrendipine (pN). Compared with the no-drug condition, aN reduced resting MBP from 137.3 +/- 7.3 (mean +/- SEM) to 112.3 +/- 9 mm Hg (p less than 0.05), increased resting HR from 72.3 +/- 6.9 to 85.3 +/- 8.8 beats/min) (p less than 0.05), increased resting CO from 6,191 +/- 508, to 8,700 +/- 1,050 ml/min (p less than 0.05), and reduced resting TPR from 1,807 +/- 119 to 1,140 +/- 228 dynes/s/cm5 (p less than 0.05). The reduction in resting MBP and TPR were unchanged by pN, whereas the increase in HR and CO were attenuated by 47 and 42%, respectively (p less than 0.05). Neither aN nor pN altered the hemodynamic responses to CPT, HG, and CE. As a result, the peak MBP and TPR values that were measured during these maneuvers were always lower (p less than 0.05) during aN and pN than in the no-drug condition. Thus, nitrendipine exerts marked antihypertensive and vasodilatatory effects that are evident at rest and during conditions elevating BP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Normal and neoplastic plasma cell membrane phenotype: studies with new monoclonal antibodies.

Three monoclonal antibodies (MoAb), named 8A, 8F6 and 62B1, reacting with plasma cell-associated antigens, were characterized. 8A was found to be positive throughout the B cell lineage maturation steps from the immature B-committed CD10+ cell to the plasma cells. 8F6 and 62B1 reactivity is restricted to more mature cells and related lymphoid malignancies. In particular 62B1 appears to be limited to hairy cells and plasma cells. The results show that it is possible to obtain reagents reacting with plasma cells by immunizing mice with cells derived from human multiple myelomas. Furthermore, the obtained results suggest that it is possible to elicit antibodies against antigens which are present throughout all the differentiation steps of the B cell lineage. These new MoAb could help in elucidating the phenotype of the plasma cells and the relationships of multiple myelomas with other B cell proliferative disorders.

Animals↗
PubMed1986

Family study of schizophrenia: exploratory analysis for relevant factors.

Two hundred twenty-nine schizophrenic patients, diagnosed according to DSM-III criteria, and their first degree relatives (except children) were studied. HLA A1 and CRAG A1 antigens were used as markers of probable dopaminergic pathology and, therefore, as possible indicators of genetic homogeneity that might identify subgroups of families with a specific and recognizable liability. Data were subjected to a logistic analysis in which the dependent variable was the presence of schizophrenia spectrum disorders in relatives, and the independent variables were the presence or absence of HLA A1 and CRAG A1 antigens, the sex of the proband, the sex of the relative, the severity of illness in the proband, and the type of relationship. The results for the entire sample demonstrate that the type of relationship, the sex of the proband, and the sex of the relative have significant effects on the risk of disorder in the relatives. In addition, the presence in the proband of one of the CRAG A1 antigens is a valid classification criterion for identifying a relatively homogeneous subgroup of families of schizophrenic patients.

Adolescent↗
PubMed1986

Effects of celiprolol on reflex control of the cardiovascular system in essential hypertension.

We have previously shown that baroreceptor control of the cardiovascular system and the cardiopulmonary receptor control of peripheral circulation are preserved or only moderately reduced during antihypertensive treatment with acebutolol or nadolol, which indicates that treatment with beta blockers with or without intrinsic sympathomimetic activity does not impair fundamental neural mechanisms involved in circulatory homeostasis. In the present study we have investigated the reflex control of circulation before and during antihypertensive treatment with celiprolol, which, in addition to its beta-blocking action, has vasodilator properties that may stem from interference with neural cardiovascular control. In six essential hypertensive subjects we measured blood pressure (intraarterial catheter), heart rate (ECG recording), central venous pressure (right atrial catheter), and forearm blood flow and resistance (plethysmography) before and during alterations in the activity of the arterial baroreceptors obtained by means of lower body suction and passive leg raising. The study was performed before and after 5-7 days of oral administration of celiprolol at 200-400 mg once a day. Compared to the values obtained in the control, condition celiprolol caused a reduction in blood pressure, a slight change in heart rate, and an increase in forearm blood flow, which indicated the occurrence of a clear-cut forearm vasodilatation. The heart rate responses to arterial baroreceptor manipulation were unchanged by celiprolol which reset the carotid baroreflex so that its tonic restraint on blood pressure increased despite the hypotension induced by the drug. The inhibitory restraint tonically exerted by the cardiopulmonary receptors on peripheral circulation was also increased by celiprolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Acebutolol↗
PubMed1986

Control of circulation by arterial baroreceptors and cardiopulmonary receptors in hypertension.

This article reviews observations made on reflex control of circulation in essential hypertension and in a few models of experimental hypertension. It is emphasized that a wide consensus exists on the fact that baroreceptor control of heart rate is impaired in essential hypertension and that this occurs not only in severe but also in mild and borderline hypertensive conditions. On the other hand, baroreceptor control of blood pressure is much less affected by chronic elevations in arterial blood pressure due to central or peripheral factors that differentially affect cardiac and vascular responses to the vagus and the sympathetic drive, respectively. Cardiopulmonary receptor control of peripheral circulation and renin release is also little affected by hypertension, and the suggestion has been made that its sensitivity may even be enhanced in early hypertensive stages and then undergoes a subsequent reduction as cardiac hypertrophy develops. Finally, the possible consequences of preservation of reflex control of circulation in hypertension are discussed. It is speculated that this phenomenon may be in part responsible for the similar percentage of blood pressure oscillations that can be observed in normotensive and borderline, moderate, and severe hypertensive subjects.

Animals↗
PubMed1985

[Maternal drug dependence and infections. Perinatal mortality].

Some toxic and infectious factors affecting pregnant drug addicts are analysed. Harmful effects on the foetus and the newborn are assessed. The problem of perinatal mortality as a result of maternal drug addiction is examined. A review of the literature reveals the mortality rate to be high.

Antigens, Viral↗
PubMed1985

[Pregnancy and drug dependence].

The complex problem of drug-taking during pregnancy is examined. Clinical and metabolic effects on the baby at birth, amounting to withdrawal effects, are described. The importance of prophylactic and therapeutic abstinence during gestation, birth and the period following birth is emphasised.

Abnormalities, Drug-Induced↗
PubMed1985

Changes in plasma catecholamines in response to reflex modulation of sympathetic vasoconstrictor tone by cardiopulmonary receptors.

The effects of selective deactivation and stimulation of cardiopulmonary receptors on plasma noradrenaline (radioenzymatic method) were studied in nine normotensive subjects by reducing and increasing central venous pressure for 20 min via lower body suction and leg-raising manoeuvres that did not alter arterial blood pressure and heart rate. Deactivation of cardiopulmonary receptors was accompanied by a rise in plasma noradrenaline that achieved a peak within 5 min (91.8 +/- 22%, mean +/- SE) and was then sustained. Stimulation of cardiopulmonary receptors was accompanied by a fall in plasma noradrenaline (-16.6 +/- 3.4%) that levelled off at the second minute and was then sustained. On average the increase and the reduction in plasma noradrenaline had a time course and a magnitude similar to the increase (80.5 +/- 10.5%) and the reduction (-28.4 +/- 5%) in forearm vascular resistance (derived from plethysmographic flow measurement) concomitantly caused by cardiopulmonary receptors. Furthermore, analysis of individual data showed that changes in plasma noradrenaline and forearm vascular resistance were linked by a positive relationship (r = 0.64). Thus the cardiopulmonary receptor reflex can produce rapid, marked and sustained changes in both plasma noradrenaline and forearm vasomotor tone. This is in sharp contrast with the previously observed inability of the carotid baroreflex to alter both these humoral and haemodynamic variables. Taken together these findings support the hypothesis that sympathetic tone to skeletal muscle is an important determinant of the concentration of plasma noradrenaline in blood.

Adult↗
PubMed1985

Reflex cardiovascular regulation in humans.

Although studies of the cardiovascular control exerted by arterial baroreceptors in man are limited by technical and ethical problems, the variable-pressure neck-chamber technique has provided a considerable amount of information about this topic. This paper focuses on the carotid baroreceptor reflex as evaluated by studies using the neck-chamber technique and examines this control in a number of physiological and pathophysiological states. The results of these studies suggest that in normotensive subjects the set-point of the reflex is located eccentrically toward its saturation, which makes this homeostatic mechanism more effective in counteracting a blood-pressure fall than a blood-pressure rise. They also suggest that the concept of an impairment of the arterial baroreflex in aging, exercise, and hypertension, though valid for the baroreceptor control of heart rate, is no longer tenable for the baroreceptor control of arterial pressure. The paper also reviews in humans the effects of arterial baroreceptors on regional circulations and on the excretion of humoral substances such as renin, and compares them with those of the cardiopulmonary receptors. It is suggested that the latter predominate over the former in the reflex modulation of plasma-renin activity, and that this is part of a homeostatic mechanism for blood-volume control.

Blood Pressure↗
PubMed1985

Acute and chronic converting enzyme inhibition reduces the vasomotor response to reflex sympathetic activation in man.

Several lines of evidence indicate that angiotensin II (ANG II) may potentiate the vascular response to sympathetic stimulation. However, there are no clear signs that this action of ANG II is physiologically relevant in man. To investigate this problem, we used the lower body negative pressure technique (LBNP, -15 mmHg) to deactivate cardiopulmonary receptors and reflexly stimulate the sympathetic nervous system. The haemodynamic (changes in blood pressure, heart rate, central venous pressure, forearm blood flow) and humoral effects [changes in plasma noradrenaline (PNA) and plasma renin activity (PRA)] of this manoeuvre were examined before and after blockade of angiotensin formation achieved by the administration of the converting enzyme inhibitor, captopril. Studies were performed in patients with essential hypertension in control conditions and after acute and chronic captopril treatment. We found that the reduction in forearm blood flow induced by LBNP was significantly diminished after acute and chronic captopril in spite of the fact that the fall in central venous pressure and the increases in PNA were similar to those observed in control conditions. In contrast, the response of renin to LBNP was enhanced, at least after acute captopril administration. These findings suggest that efficiency of the reflexes originating from the cardiopulmonary receptors is impaired after captopril. Angiotensin II contributes to the vasoconstrictive ability of the sympathetic nervous system, either through a direct vascular action or by enhancing the vascular responsiveness to noradrenaline stimulation. However, this sympathetic facilitatory action of ANG II does not appear to be extended on the adrenergic mechanisms which regulate renin release.

Adult↗
PubMed1984

Twenty-four-hour blood pressure profile and blood pressure variability in untreated hypertension and during antihypertensive treatment by once-a-day nadolol.

First, blood pressure and heart rate variability was studied in 89 normotensive and hypertensive ambulatory subjects with the use of an intra-arterial monitoring device. Short- and long-term variabilities were analyzed by computer. Absolute variabilities (standard deviations) were greatest in patients with hypertension, but relative variabilities (variation coefficients, i.e., standard deviations as percent of means) were slightly lower in the subjects with more severe hypertension. Second, the effect of nadolol on 24-hour blood pressure and heart rate values and on their variability was assessed in seven ambulatory patients with essential hypertension by means of the same intra-arterial device and computer analysis. Two recording sessions were performed (1) without treatment and (2) after 10 days' administration of nadolol once a day (dose range, 80 to 320 mg). Nadolol, given once a day, was shown to reduce blood pressure uniformly throughout the 24-hour period without loss of activity in the hours farthest from administration. The lack of alteration in relative blood pressure variability suggests that nadolol lowers blood pressure without interfering with the mechanisms involved in cardiovascular homeostasis. Reduction in heart rate variability after nadolol suggests less chance of tachycardia episodes in patients with angina and/or arrhythmias receiving nadolol.

Adrenergic beta-Antagonists↗
PubMed1984

Arterial baroreceptor control of blood pressure in man.

Information on arterial baroreceptor control of circulation is much more restricted in man than in animals, largely because of the limitations in the techniques available in humans for this type of study. However, recent utilization of the neck chamber technique that addresses the primary function of an arterial baroreflex, i.e. blood pressure control, has provided a significant amount of information. This paper describes baroreceptor control of blood pressure as derived from neck chamber studies in normal people and discusses its modifications by exercise and ageing, and its participation in a phenomenon such as spontaneous blood pressure variability. The description given here is focused on aspects of this baroreceptor control that have changed the concept of the overall arterial baroreceptor function developed by means of techniques for studying only baroreceptor influences on heart rate.

Adult↗
PubMed1984

Role of cardiopulmonary receptors in reflex control of renin release in man.

Animal studies have shown that renin release is reflexly modulated by cardiopulmonary and arterial baroreceptors, and that during changes in posture the former receptors play a major role. This role has been challenged in man, however, by reflex modulation of renin secretion which has been claimed to take place only if arterial and cardiopulmonary receptor areas are engaged together. We studied 19 normotensive and essential hypertensive subjects in which plasma renin activity was assessed by radioimmunoassay during a mild 20 min increase and a mild 20 min reduction in central venous pressure (+1.1 +/- 0.2 mmHg and -2.6 +/- 0.4 mmHg). The increase and reduction in central venous pressure were accompanied by no change in systolic blood pressure, diastolic blood pressure and heart rate which indicated that the increased and reduced stimulus had involved only cardiopulmonary receptors and not arterial baroreceptors as well. During the increase in central venous pressure plasma renin activity showed a significant (P less than 0.01) reduction (-18 +/- 3%) whereas during the reduction in central venous pressure it showed a significant (P less than 0.01) and more marked increased (+64 +/- 17%). The plasma renin activity increase observed during lower body suction was not significantly different from that observed during a 20 min tilting, a manoeuvre that reduced central venous pressure to an extent similar to that observed during lower body suction, but that also deactivated carotid baroreceptors by positioning the carotid sinuses above the heart and reducing their transmural pressure. Thus in normotensive and hypertensive humans renin release can be reflexly modulated by selective engagement of cardiopulmonary receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Alterations in plasma noradrenaline in response to reflex modulation of sympathetic vasoconstrictor tone to skeletal muscles.

In man, stimulation and deactivation of carotid baroreceptors are accompanied by sympathetically-induced reduction and increase in total peripheral resistance, but not by alterations in plasma noradrenaline. This has been explained by the inability of arterial baroreflexes to sustainedly modulate sympathetic tone to skeletal muscle vessels on which plasma noradrenaline has been assumed largely to depend. In the present study nine subjects were submitted to procedures that cause a sustained alteration in muscle sympathetic vasoconstrictor tone, i.e. deactivation and stimulation of cardiopulmonary receptors. Cardiopulmonary receptor deactivation was achieved by a 20-min reduction in central venous pressure via application of subatmospheric pressure to the lower body, and the cardiopulmonary receptor stimulation by a 20-min increase in central venous pressure via passive leg raising. Plasma noradrenaline was measured radioenzymatically on blood sampled from an antecubital vein or the right atrium before, and at the 2nd, 5th, 10th and 20th min of each manoeuvre. The noradrenaline measurements were coupled with measurements of arterial blood pressure, heart rate and forearm blood flow and resistance (plethysmographic method). During reduction and increase in central venous pressure, blood pressure and heart rate did not change, whereas forearm vascular resistance markedly rose and fell with a peak response at 5 min and a subsequent plateau. These changes were accompanied by a marked rise and fall in plasma noradrenaline which also peaked within 5 min and were then sustained. Changes in forearm vascular resistance and noradrenaline showed a close qualitative parallelism, each increase in the former being accompanied by an increase in the latter, and vice-versa.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗