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Biomedical subjects

N V Olsen

Publications and source records attributed to N V Olsen.

At least 37 records · Page 2Linked to original sources
PubMed1996

Human erythropoietin response to hypocapnic hypoxia, normocapnic hypoxia, and hypocapnic normoxia.

This study investigated the human erythropoietin (EPO) response to short-term hypocapnic hypoxia, its relationship to a normoxic or hypoxic increase of the haemoglobin oxygen affinity, and its suppression by the addition of CO2 to the hypoxic gas. On separate days, eight healthy male subjects were exposed to 2 h each of hypocapnic hypoxia, normocapnic hypoxia, hypocapnic normoxia, and normal breathing of room air (control experiment). During the control experiment, serum-EPO showed significant variations (ANOVA P = 0.047) with a 15% increase in mean values. The serum-EPO measured in the other experiments were corrected for these spontaneous variations in each individual. At 2 h after ending hypocapnic hypoxia (10% O2 in nitrogen), mean serum-EPO increased by 28% [baseline 8.00 (SEM 0.84) U.l-1, post-hypoxia 10.24 (SEM 0.95) U.l-1, P = 0.005]. Normocapnic hypoxia was produced by the addition of CO2 (10% Co2 with 10% O2) to the hypoxic gas mixture. This elicited an increased ventilation, unaltered arterial pH and haemoglobin oxygen affinity, a lower degree of hypoxia than during hypocapnic hypoxia, and no significant changes in serum-EPO (ANOVA P > 0.05). Hypocapnic normoxia, produced by hyperventilation of room air, elicited a normoxic increase in the haemoglobin oxygen affinity without changing serum-EPO. Among the measured blood gas and acid-base parameters, only the partial pressures of oxygen in arterial blood during hypocapnic hypoxia were related to the peak values of serum-EPO (r = -0.81, P = 0.01). The present human EPO responses to hypoxia were lower than those which have previously been reported in rodents and humans. In contrast with the earlier rodent studies, it was found that human EPO production could not be triggered by short-term increases in pH and haemoglobin oxygen affinity per se, and the human EPO response to hypoxia could be suppressed by concomitant normocapnia without acidosis.

Adult↗
PubMed1996

Endogenous versus exogenous lithium clearance for evaluation of dopamine-induced changes in renal tubular function.

1. The present randomized, double-blind cross-over study compared endogenous and exogenous lithium clearance (CLi) for estimation of the effect of dopamine on tubular sodium reabsorption. Twelve normal, salt-repleted male subjects were investigated on three different occasions with either placebo or 450 mg or 600 mg of lithium given in random order at 22.00 hours. After an overnight fast, renal clearance studies were performed during a 1 h baseline period and subsequently during the second hour of an infusion of 3 micrograms min-1 kg-1 of dopamine. 2. Baseline values of endogenous CLi and fractional excretion of lithium (FELi) [27.0 (23.5-30.5) ml/min and 24.2 (20.3-28.2)% (means with 95% confidence interval)] were lower than exogenous values [lithium, 450 mg: 32.7 (29.9-35.4) ml/min (P < 0.05) and 27.4 (25.2-29.6)% (P < 0.05); lithium, 600 mg: 33.4 (29.2-37.6)ml/min (P < 0.05) and 28.6 (26.3-31.0)% (P < 0.01)]. Both test doses of lithium increased the baseline sodium clearance (CNa), but glomerular filtration rate and urine flow rate remained unchanged. 3. Dopamine increased CNa to similar values on the three study days. CLi increased to 40.9 (35.5-46.5) ml/min (endogenous lithium, P < 0.001), 43.2 (40.8-45.6) ml/min (450 mg of lithium, P < 0.01) and 44.9 (41.3-48.4) ml/min (600 mg of lithium, P < 0.001), respectively. FELi increased to 32.2 (27.5-37.0)% (P < 0.01), 35.4 (33.0-37.7)% (P < 0.01) and 35.9 (32.8-38.9)% (P < 0.01), respectively. Values during dopamine infusion did not differ significantly. 4. The lower baseline values of endogenous CLi and FELi compared with exogenous values suggest that CLi in humans depends on the plasma concentrations of lithium. However, the effect of dopamine on CLi and FELi was expressed to the same extent with endogenous and exogenous lithium, indicating that the two methods are interchangeable for estimation of dopamine-induced changes in tubular function.

Adult↗
PubMed1996

Renal effects of amino acids and dopamine in renal transplant recipients treated with or without cyclosporin A.

1. The nephrotoxic effects of cyclosporin A may diminish the ability of the transplanted kidney to increase the glomerular filtration rate and effective renal plasma flow during infusion of dopamine or amino acids. 2. The present study included 16 renal transplant recipients transplanted for more than 6 months. Eight of the patients were on immunosuppressive treatment including cyclosporin A [cyclosporin A group; cyclosporin A dose, 2.7 +/- 0.4 mg/kg; S-creatinine, 105 +/- 12 mumol/l (means +/- SEM)], whereas eight patients had never received cyclosporin A (non-cyclosporin A group; S-creatinine, 89 +/- 6 mumol/l). The renal response to infusion of dopamine and of amino acids was investigated on two separate days. All clearance measurements were carried out at nadir cyclosporin A blood levels. 3. Effective renal plasma flow increased significantly in the non-cyclosporin A group and cyclosporin A group by 31.0 +/- 4.1% and 35.9 +/- 6.6%, respectively, during infusion of dopamine, and by 18.7 +/- 6.7% and 13.9 +/- 5.3%, respectively, during infusion of amino acids. Glomerular filtration rate increased significantly in the non-cyclosporin A group and cyclosporin A group by 15.7 +/- 3.3% and 18.3 +/- 4.7%, respectively, during infusion of dopamine, and by 18.9 +/- 4.5% and 15.0 +/- 3.7%, respectively, during infusion of amino acids. 4. Furthermore, the amino acid- and dopamine-induced increases in proximal tubular outflow (renal clearance of lithium) and calculated changes in renal proximal and distal tubular handling of sodium (and water) were comparable between the two groups of patients. Dopamine caused significant natriuresis in both groups. 5. In conclusion, low-dose cyclosporin A seems not to attenuate the renal haemodynamic and tubular response to infusions of amino acids and of dopamine in renal transplant recipients with a good graft function.

Adult↗
PubMed1996

High altitude-induced albuminuria in normal man is enhanced by infusion of low-dose dopamine.

Renal function and the urinary excretion rate of albumin (Ualb) at rest and during infusion of dopamine (3 micrograms kg-1 min-1) were investigated in eight normal volunteers at sea level and 48 h after a rapid, passive ascent to an altitude of 4350 m. Oxygen saturation decreased to 81% (77-85) (median with quartiles in parentheses) at high altitude. High altitude hypoxia increased Ualb from 3.2 micrograms min-1 (2.7-3.5) to 5.0 micrograms min-1 (3.3-6.6) (p < 0.05); increased mean arterial blood pressure from 80 mmHg (73-95) to 102 mmHg (96 108) (p < 0.01); decreased the effective renal plasma flow (ERPF) from 465 ml min-1 (412-503) to 410 ml min-1 (385-451) (p < 0.05), and increased the filtration fraction from 24% (22-27) to 28% (26-29) (p < 0.01). Glomerular filtration rate (GFR), and the renal clearances of lithium (CLi) and sodium (CNa) remained unchanged at high altitude. Dopamine increased ERPF, GFR, CLi, CNa, and decreased the filtration fraction in both environments. Infusion of dopamine further increased Ualb to 10.5 micrograms min-1 (5.5-64.8) (p < 0.05) at high altitude, but had no effect on Ualb at sea level. In conclusion, high altitude hypoxia per se increases the urinary excretion rate of albumin, which is further increased by the renal vasodilating drug dopamine. This effect of dopamine at high altitude may result from combined effects of the increase in renal plasma flow and a hypoxia-induced increase in the glomerular capillary permeability to albumin.

Adult↗
PubMed1995

[Renal side-effects of intraoperative and postoperative pain treatment with non-steroidal anti-inflammatory drugs].

Non-steroidal anti-inflammatory drugs (NSAID) are now commonly used in the treatment of postoperative pain. In normovolaemic conditions, prostaglandins do not seem to play a substantial role in maintaining renal function. However, numerous studies have shown that during activation of vasoconstrictor systems the synthesis of renal prostaglandins counteracts the vasoconstrictor effects and thereby maintains renal function. In animals, renal blood flow and GFR are markedly decreased when an NSAID is administered in the presence of renal hypoperfusion. Major surgery decreases renal function secondary to stimulation of the adrenosympathetic system and the renin-angiotensin system, and it has previously been demonstrated that maintenance of renal blood flow during laparotomy in dogs depends on an intact prostaglandin synthesis. Perioperative effects of NSAIDs are only sparsely investigated in humans, and studies on the effect on renal haemodynamics have not been presented. As in unanaesthetized volunteers, NSAID have been found to decrease the postoperative excretion of water, sodium and potassium. It therefore still remains unclarified whether general anaesthesia and surgery increase the risk of renal side effects of NSAIDs. Because of the potential risk of peri- and postoperative complications that may further deteriorate renal function, NSAIDs should not be used preoperatively, and not in patients in unstable haemodynamic states.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1995

[Cardiovascular effects of a calcium channel blocker in hypoxia caused by altitude].

OBJECTIVE: High altitude pulmonary oedema can be successfully treated and prevented by calcium channel blockers. Moreover, calcium entering in the cells could explain the congestive phenomena of acute mountain sickness (AMS). These findings led us to study the action of a calcium channel blocker, isradipine, in the prevention of non-complicated AMS. METHODS: In a double blind randomized study, 20 healthy volunteers received 5 mg of isradipine (n = 6) or placebo (n = 6) for 8 days. After 5 days of treatment in normoxia, the subjects were rapidly transported to an altitude of 4350 m. The efficiency of the treatment was then estimated by the AMS symptom score, haemodynamic parameters and renal function. RESULTS: The administration of isradipine did not significantly modify AMS symptom score nor most of other parameters measured in high altitude hypoxia. Heart rate was an average of 15 b/min lower in the isradipine group, probably because of a direct action of isradipine on the sinus node. Otherwise, the effects of hypoxia were similar in both groups and were in accordance with the literature. There was no clear explanation for the increase in cardiac output and stroke volume when the subjects moved from supine to standing position. Renal blood flow, measured by Doppler or para-aminohippuric acid clearance was not modified by hypoxia. Cerebral blood flow was elevated, due to the direct vasodilator effect of hypoxia. However this increase did not seem to be the main mechanism responsible for the congestive phenomena. On the other hand, the increase in capillary permeability (demonstrated by the increased transcapillary escape rate of albumin, and albuminuria) appeared to play a major role in the pathogenesis of AMS and high altitude cerebral oedema. Isradipine had no protective effect on these phenomena and its use should be restricted to the treatment of high altitude pulmonary oedema.

Adult↗
PubMed1995

Comparison of cardiac output measurement techniques: thermodilution, Doppler, CO2-rebreathing and the direct Fick method.

Simultaneously measured cardiac output obtained by thermodilution (TD), transcutaneous suprasternal ultrasonic Doppler (DOP), CO2-rebreathing (CR) and the direct Fick method (FI) were compared in eleven healthy subjects in a supine position (SU), a sitting position (SI), and during sitting exercise at a workload of 50 W (EX). The agreements between the techniques, two by two, were expressed as the bias calculated as the averaged differences between the techniques. Precision was expressed as the standard deviation of the bias. The overall agreement (bias +/- precision) between TD, DOP and CR respectively and FI were 2.3 +/- 1.6, -0.1 +/- 1.4, and -0.2 +/- 1.1 l/min. TD overestimated cardiac output consistently in SU, SI and EX. DOP was in-accurate during EX and agreed well with FI in SU and SI. CR agreed closely with FI in SI and EX, but values were underestimated in SU. The overall agreement between DOP and CR, respectively, and TD were 2.5 +/- 2.2 and 2.6 +/- 1.6 l/min. The overall agreement between DOP and CR was 0.1 +/- 1.6 l/min. In conclusion, TD overestimated cardiac output compared to the other techniques and the poor agreement has to be taken into consideration especially in measures of low values. The precision of DOP and CR against FI seems to be within clinically acceptable limits, and these methods may provide interchangeable alternatives to the invasive Fick method.

Adult↗
PubMed1995

Effect of hypoxaemia on water and sodium homeostatic hormones and renal function.

Changes in body fluid homeostasis during acute hypoxaemia suggest a crucial role of renal function in acclimatization processes. Hypoxaemia stimulates sympathetic nervous activity, and also the cardiovascular system is affected with increases in heart rate and cardiac output. In most subjects, a hypoxic ventilatory response produces hypocapnia and respiratory alkalosis. Acute hypoxaemia depresses aldosterone secretion secondary to a direct effect on adrenal cells. Also plasma renin is decreased in resting hypoxaemic conditions, but the mechanism remains unknown. These hormonal changes may have the advantage of opposing excessive sodium and water retention, which characterizes acute mountain sickness. Short-term isocapnic or hypocapnic hypoxaemia in spontaneously breathing humans causes moderate if any increases in renal blood flow and only minor changes in GFR. In contrast, renal blood flow and GFR decreases during hypercapnic hypoxaemia. Renal clearance studies in humans after 24-48 hours in altitude hypoxia (4,350 m) demonstrate that glomerular and tubular function is only slightly changed in spite of marked depression of the renin-aldosterone system and increased plasma levels of norepinephrine. However, renal vascular tone may increase most probably secondary to the increased adrenosympathetic activity. In the first hours, acute hypoxaemia may induce an increased excretion of sodium and water. Previous studies suggest that the natriuretic response is caused by decreased reabsorption of sodium and bicarbonate in the proximal tubules secondary to the associated hyperventilation and hypocapnia. After 6 hours, sodium and water excretion is normalized or even depressed, dependent on the severity of acute mountain sickness. In view of the prompt increase in sodium and water excretion found during short-term hypoxaemia, the absence of such a response to more prolonged hypoxaemia suggests an adaptive time-dependent course of renal functional changes in hypoxaemia. Taken together, previous studies suggest that effects of acute hypoxaemia on renal haemodynamics are minor compared with effects on cerebral and coronary circulation. This might be the result of an appropriate resetting of autoregulatory mechanisms that would maintain the role of the kidney as a major sense organ to hypoxaemia and, subsequently, as a mediator of plasma volume regulation and erythropoietin synthesis.

Acclimatization↗
PubMed1995

No effect of dietary fish oil on renal hemodynamics, tubular function, and renal functional reserve in long-term renal transplant recipients.

Dietary supplementation with fish oil rich in n-3 polyunsaturated fatty acids has been suggested to protect the kidney against cyclosporin A (CsA) toxicity. This study investigated the effects of a 10-wk dietary supplementation with fish oil on renal function and renal functional reserve in healthy volunteers (N = 9) and two groups of stable long-term kidney-transplanted patients treated with maintenance low-dose CsA (3.0 +/- 0.6 mg/kg; N = 9) or without CsA (N = 9). After an overnight fast, the subjects were water loaded, and clearance studies were performed, postponing morning medication. GFR and effective RPF were measured as the renal clearances of (99mTc)DTPA and (131I)hippuran, respectively. Renal tubular function was evaluated by use of the renal clearance of lithium and the urinary excretion of beta 2-microglobulin. Fish oil did not change baseline values of effective RPF, GFR, lithium clearance, and urinary excretion of beta 2-microglobulin in any of the groups. The infusion of amino acids induced a comparable increase in GFR, lithium clearance, and the urinary excretion rate of beta 2-microglobulin in all three groups with no additional effect of fish oil. Thus, long-term renal transplant recipients treated with a low maintenance dose of CsA had a well-preserved renal functional reserve, and dietary supplementation with fish oil in these patients did not improve renal function.

Adult↗
PubMed1994

Effects of acute beta-adrenoceptor blockade with metoprolol on the renal response to dopamine in normal humans.

The present study investigated the contribution of adrenergic beta 1-receptor stimulation to the cardiovascular and renal effects of low-dose dopamine in eight normal, water-loaded humans. Metoprolol (100 mg) or placebo was administered orally at 08.00 h in a randomized, double-blind fashion on two different days. Renal clearance studies were performed during a 1 h baseline period, two 1 h periods with dopamine infusion (3 micrograms kg-1 min-1), and a 1 h recovery period. Cardiac output was measured by an ultrasonic Doppler method, and lithium clearance (CLLi) was used to estimate proximal tubular outflow. Baseline values of heart rate, systolic pressure and mean arterial pressure decreased with metoprolol compared with placebo, but cardiac output, effective renal plasma flow (ERPF) and glomerular filtration rate (GFR) were not significantly changed. Metoprolol significantly decreased baseline CLLi and sodium clearance (CLNa) by 19% (P < 0.01) and 34% (P < 0.01), respectively. Metoprolol blunted the dopamine-induced increases in heart rate and systolic pressure, but cardiac output increased to the same extent on both study days by 26% (placebo, P < 0.05) and by 31% (metoprolol, P < 0.01), respectively. With and without metoprolol, dopamine did not significantly change GFR, and the percentage increases in ERPF were similar on the two study days (40% (P < 0.001) and 42% (P < 0.001), respectively). Dopamine increased CLLi and CLNa by 31% (P < 0.01) and 114% (P < 0.01), respectively, with placebo, and by 36% (P < 0.01) and 114% (P < 0.01), respectively, with metoprolol. Values during infusion remained significantly lower with metoprolol compared with placebo.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Albuminuria and overall capillary permeability of albumin in acute altitude hypoxia.

The mechanism of proteinuria at high altitude is unclear. Renal function and urinary excretion rate of albumin (Ualb) at rest and during submaximal exercise and transcapillary escape rate of 125I-labeled albumin (TERalb) were investigated in 12 normal volunteers at sea level and after rapid and passive ascent to 4,350 m. The calcium antagonist isradipine (5 mg/day; n = 6) or placebo (n = 6) was administered to abolish hypoxia-induced rises in blood pressure. Lithium clearance and urinary excretion of beta 2-microglobulin were used to evaluate renal tubular function. High altitude increased Ualb from 2.8 to > 5.0 micrograms/min in both groups (P < 0.05). In the placebo group, high altitude significantly increased filtration fraction (P < 0.05), but this response was abolished by isradipine. Lithium clearance and urinary excretion of beta 2-microglobulin remained unchanged by hypoxia in both groups. Exercise did not reveal any further renal dysfunction. In both groups, high altitude increased TERalb from 4.8 to > 6.7%/h (P < 0.05). In conclusion, acute altitude hypoxia increases Ualb despite unchanged tubular function and independent of effects of isradipine on filtration fraction. The elevated TERalb suggests an overall increase in capillary permeability, including the glomerular endothelium, as the critical factor in high-altitude induced albuminuria.

Adult↗
PubMed1993

Lithium clearance method and the renal response to low-dose dopamine in man: a randomized, controlled study.

1. The effect of a single dose of lithium on renal function before and during intravenous infusion of dopamine (3 micrograms min-1 kg-1) was investigated in 12 healthy males. In a double-blind and randomized design, 450mg or 600mg of lithium carbonate or placebo was administered orally at 22.00 hours on three different occasions. After an overnight fast, the subjects were water-loaded and clearance studies were started at 09.00 hours with a 1h baseline period and three 1h periods during dopamine infusion. 2. Baseline sodium clearance with placebo was 0.65 +/- 0.35 ml/min, but with lithium it increased to 1.25 +/- 0.44 (P < 0.001) and 1.17 +/- 0.46 ml/min (P < 0.01) after 450 and 600mg, respectively. Urine flow rates were unchanged compared with placebo. Lithium did not significantly affect glomerular filtration rate, but both doses slightly increased effective renal plasma flow by 7% (P < 0.05) and 10% (P < 0.01), respectively. 3. The maximal natriuretic and diuretic effects of dopamine were not reduced by lithium, but the percentage increases in sodium clearance were significantly diminished after 450mg (P < 0.01) and 600mg (P < 0.001) of lithium. Lithium had no effect on dopamine-induced changes in effective renal plasma flow, glomerular filtration rate or osmolal clearance. Neither lithium nor dopamine influenced plasma concentrations of renin, aldosterone or atrial natriuretic peptide. 4. In conclusion, single test doses of lithium, as normally used in lithium clearance studies, increase baseline values of sodium clearance and effective renal plasma flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Dopamine, dobutamine, and dopexamine. A comparison of renal effects in unanesthetized human volunteers.

BACKGROUND: Recently, dopexamine (DX), which acts via adrenergic beta 2 and dopaminergic DA1 receptors, has been introduced in the treatment of low cardiac output states. However, the renal effects of DX have not been compared to those produced by equipotent inotropic doses of dopamine (DA), which predominantly stimulates DA1 and DA2 receptors, and of dobutamine (DB), which stimulates beta 1 but not DA receptors. The current study tested the null hypothesis that, with equal increases in cardiac output, DX, DA, and DB would have similar effects on renal function. METHODS: Each drug was given for 2 h on three different occasions to eight normal subjects in doses adjusted to produce a similar 30-35% increase in cardiac output. Effective renal plasma flow (ERPF) and glomerular filtration rate (GFR) were measured as renal clearances of 131I-hippuran and 99mTc-DTPA, respectively. Lithium clearance (CLi) was used as an index of proximal tubular outflow. RESULTS: Doses of DA, DX, and DB were 2.90 +/- 0.19, 1.00 +/- 0.02, and 4.92 +/- 0.40 microgram.kg-1.min-1, respectively. Dopamine and DX increased ERPF by 23% and 10%, respectively, whereas ERPF remained unchanged during DB. The increase in ERPF was smaller during DX compared with DA. The GFR remained unchanged during DA and DB, but increased during DX (7%). The CLi increased by 35% and 30% during DA and DX, respectively, but was not changed by DB. Calculated absolute proximal reabsorption rate (APR = GFR--CLi) decreased by 13% during DA, but remained unchanged during DB and DX. Dopamine increased sodium clearance (CNa) by 103%, but the changes during DX and DB were not significant. Only DA decreased fractional distal reabsorption (FDRNa = 1--CNa/CLi). CONCLUSIONS: The findings are consistent with a specific, renal-vasodilating effect of DA and DX. However, in the current doses, this effect of DX was of lesser magnitude compared with that of DA. Only DA significantly increased CNa, and the decreases in APR and FDRNa indicate that an effect on tubular reabsorption rate contributed to the natriuresis.

Adult↗
PubMed1993

Renal hemodynamics, tubular function, and response to low-dose dopamine during acute hypoxia in humans.

Renal function was investigated in eight normal subjects before and during infusion of dopamine (3 micrograms.kg-1 x min-1) at sea level (SL) and at high altitude (HA, 4,350 m). Lithium clearance (CLi) was used as an index of proximal tubular outflow. HA significantly increased arterial pressure, heart rate, and plasma norepinephrine. Effective renal plasma flow (ERPF) decreased at HA by 10% (P < 0.05), but glomerular filtration rate (GFR), CLi, sodium clearance (CNa), and urine flow remained unchanged compared with SL. Dopamine at SL and HA increased ERPF by 47% (P < 0.001) and 30% (P < 0.01), respectively, but the increase at HA was smaller than that at SL (P < 0.05). Dopamine increased GFR only at SL. CLi and CNa increased by 29% (P < 0.001) and 108% (P < 0.001) at SL and by 23% (P < 0.01) and 108% (P < 0.001) at HA. Whereas dopamine at SL increased urine flow by 46% (P < 0.01), this response was abolished at HA, and free water clearance decreased (P < 0.05). The decreased ERPF at HA suggests a constriction of the renal arterioles secondary to increased adrenergic nervous activity. Although the effect of dopamine on ERPF was attenuated in hypoxia, dopamine-induced increases in CLi and CNa remained unaltered, suggesting that natriuresis in both environments was secondary to an increased outflow from the proximal tubules. The absence of a diuretic response to dopamine at HA seemed to be caused by an effect on distal tubular function.

Acute Disease↗
PubMed1992

Effects of acute hypoxia on renal and endocrine function at rest and during graded exercise in hydrated subjects.

Renal effects of altitude hypoxia are unclear. Renal and hormonal function was investigated in eight males at rest and during graded exercise at sea level (SL) and 48 h after rapid ascent to 4,350 m (HA). HA did not change resting values of effective renal plasma flow (ERPF), glomerular filtration rate (GFR), sodium clearance (CNa), urine flow, or lithium clearance (CLi), which was used as an index of proximal tubular outflow. At rest, HA increased plasma norepinephrine concentration and decreased plasma concentrations of renin and aldosterone. Exercise decreased ERPF similarly in both environments. Normoxic exercise progressively reduced GFR, but at HA GFR only decreased during heavy exercise. This resulted in a higher filtration fraction during light and moderate hypoxic exercise. However, calculated absolute proximal reabsorption rate (GFR-CLi) at HA was higher during low-intensity exercise, and there were no significant differences between exercise-induced decreases in CLi, CNa, and urine flow at HA compared with SL. Exercise gradually increased plasma norepinephrine, but values were higher at HA during light and moderate exercise. The small changes in the renal response to low-intensity hypoxic exercise may be secondary to increased adrenosympathetic activity. However, antidiuretic and antinatriuretic effects of exercise were maintained in hypoxia and in both environments seemed to be the consequence of decreased proximal tubular outflow. The results demonstrate that renal glomerular and tubular function is well preserved in acute hypoxia despite marked hormonal changes.

Adult↗
PubMed1991

Split-dose atropine versus glycopyrrolate with neostigmine for reversal of gallamine-induced neuromuscular blockade.

The effects of a split-dose of atropine sulphate versus a single dose of glycopyrrolate given with neostigmine for the reversal of gallamine-induced neuromuscular blockade were studied in 55 patients undergoing gynaecological surgery. The patients were randomized to receive either a single dose of glycopyrrolate (7 micrograms.kg-1) or two doses of atropine (8 micrograms.kg-1 each), given with an interval of 1 min. There were no differences between the two methods with respect to percentage heart rate changes, salivation or arousal time. Four patients demonstrated cardiac arhythmias in the atropine group, whereas none occurred in the glycopyrrolate group (P less than 0.05). It is concluded that a split-dose of atropine has similar chronotropic effects to a single dose of glycopyrrolate for the reversal of gallamine-induced neuromuscular blockade. However, the finding of a higher incidence of cardiac arrhythmias in the atropine group suggests that this reversal regime should be reserved for patients without cardiac disease.

Adult↗