摘要:

SUMMARY1We examined the preganglionic splanchnic nerve activity and postganglionic renal nerve activity before and after a local injection of naloxone (20 ug/kg) into the coeliac ganglion of anaesthetized rabbits. This was done during graded hypertension, induced by the administration of phenylephrine (0.5‐10 ug/kg, i.v.) and with selective intraganglionic injection of methionine‐enkephalin (ME) and bunitrolol, which is a beta‐blocker.2During hypertension both pre‐and postganglionic discharge decreased, but only postganglionic discharge was inhibited by naloxone treatment into the ganglion.3Local injection of ME (0.1‐10 ug/kg) into the coeliac ganglion decreased postganglionic activity by 9.0 ± 1.0 to 41.2 ± 4.7% from control, and this decrease was inhibited by naloxone.4Administration of bunitrolol (1‐300 ug/kg) decreased postganglionic discharge by 3.9 ± 1.4 to 39.7 + 2.4% of the control and this decrease was also inhibited by naloxone.5These results suggest that opioid receptors in the coeliac ganglion play an inhibitory role in neural ganglionic transmission and that this inhibitory action reduces postganglionic sympath

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1989.tb03003.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SUMMARY1The effects of sodium loading on cardiopulmonary baroreflex control of forearm vasoconstriction were studied using lower body negative pressure (LBNP) in 12 healthy young subjects.2Before and during sodium loading, there was no significant change in mean blood pressure, heart rate, central venous pressure (CVP) or forearm vascular resistance (FVR).3The degree of reflex increase in FVR during LBNP at –10, –20, and –40 mmHg was significantly greater during sodium loading than regular diet.4During sodium loading, the slope of the regression line relating percent change in FVR and change in CVP was significantly increased.5These results suggest that sodium loading augments cardiopulmonary baroreflex sensitivity of FVR in normotensive subjects without a family history of hyperte

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1989.tb03004.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SUMMARY1Continuous ambulatory arterial pressure monitoring was performed by telemetry in 34 hypertensive and four normotensive subjects and arterial baroreflex sensitivity was evaluated by computer analysis of pulse wave. Three consecutive pulses were selected, on two criteria, from the 24 h recording: (i) progressive and linear increase or decrease in systolic arterial pressure and heart period, (ii) change of systolic arterial pressure in three pulses exceeds a threshold value. The systolic arterial pressure and heart period of three pulses were averaged and the slopes of systolic arterial pressure and heart period were calculated as baroreflex sensitivity.2When the threshold value was set to 5 mmHg, baroreflex sensitivity measured by the present method correlated with baroreflex sensitivity as measured by the phenylephrine method (r= 0.667, P<0.001).3The baroreflex sensitivity from the pressor‐bradycardia and the depressor‐tachycardia reflex decreased as threshold value was increased from 3 to 4 mmHg to over 20 mmHg. With the pressor‐bradycardia reflex, the initial systolic arterial pressure of three pulses did not change, but the initial heart period shortened progressively as the threshold increased. With the depressor‐tachycardia reflex, the initial systolic arterial pressure increased and the initial heart period shortened progressively. This suggests that the sensitivity of arterial baroreflex changes dynamically according to input of reflex arc during daily a

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1989.tb03005.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SUMMARY1The effects of passive leg elevation on the forearm circulation were compared in 14 borderline hypertensive and 16 normotensive men.2In the supine position, mean arterial pressure (MAP), heart rate (HR) and forearm blood flow (FBF) were significantly greater in borderline hypertensives.3With leg raising, MAP and HR did not change significantly from basal values. FBF increased by +0.6 ± 0.2 (s.e.m.) mL/min/100 mL P<0.02) in normotensives and by + 1.3 ± 0.2 mL/min/100 mL P<0.001) in hypertensives(Pfor difference between groups<0.05

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1989.tb03006.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SUMMARY1The aim of the present study was to examine the influence of the carotid baroreceptors on the peripheral vascular responses during static exercise and its interference with the‘central command’and the ergoreceptors.2Ten healthy subjects performed an isometric handgrip with 30% of maximal voluntary contraction for 1.5 min. Five seconds prior to the end of the exercise the arterial circulation to the exercising forearm muscles was occluded for 1.5 min. The carotid baroreceptors were stimulated by neck suction at –40 mmHg for 0.5 min in each period, and also during control and recovery phase. Contralateral forearm and calf blood flow were measured simultaneously with ECG‐triggered venous occlusion plethysmography.3The present findings suggest that there are‘central command’and ergoreceptors which modulate carotid baroreflex function to the afferent output to the heart and the peripheral

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1989.tb03007.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SUMMARY1To clarify whether acute changes in the properties of baroreflexes can occur in man, we evaluated the time course of baroreflex control of heart rate and cardiopulmonary baroreflex control of forearm vascular resistance (FVR) over 240 min after intravenous administration of propranolol (0.2 mg/kg) in 13 healthy young men.2Systolic and diastolic blood pressure remained unchanged after propranolol. Propranolol significantly decreased cardiac index and heart rate, and significantly increased total peripheral resistance. These effects remained unchanged for 240 min after propranolol.3Baroreflex control of heart rate was significantly augmented immediately after, and at 30, 60 min after propranolol, but partly reverted to the initial level afterwards. Cardiopulmonary baroreflex control of FVR was reduced immediately after, and at 30, 60 min after propranolol, but partly reverted to the initial level afterwards. Pressor responses to phenylephrine was reduced immediately after propranolol, but no significant differences were observed after 30 min.4These results suggest that acute changes in the properties of baroreflexes occur in man after propranolol.

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1989.tb03008.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SUMMARY1Young male Sprague‐Dawley rats were fed on either solid regular rat chow, control liquid diet or liquid diet containing alcohol for 26 weeks.2Phenylephrine (0.5, 1, 2 or 4 ug/kg) was injected to monitor the reflexogenic bradycardia and nitroprusside (2, 4, 8 or 16 ug/kg) was also used to establish the relationship between drug‐induced hypotension and baroreceptor‐mediated tachycardia.3Multiunit renal nerve activity was determined under pentobarbitone anaesthesia as an index of sympathetic nerve activity during the treatment with phenylephrine or nitroprusside.4Alcohol‐fed rats showed greater nerve responses to phenylephrine without corresponding decrease in heart rate, which suggests alcohol directly affects arterial wall compliance. This study does not support the contention that dietary alcohol increases blood pressure and it impairs significantly the baroreceptor f

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1989.tb03009.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY