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HAEMODYNAMIC AND HORMONAL EFFECTS OF PRAZOSIN ON HEAD‐UP TILT IN ESSENTIAL HYPERTENSIVE PATIENTS: COMPARISON WITH THOSE OF PROPRANOLOL
Author(s) -
Kida Osamu,
Morotomi Yasuyuki,
Higa Toshinobu,
Kodama Kenji,
Someya Noriyuki,
Tanaka Kenjiro
Publication year - 1984
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1984.tb00252.x
Subject(s) - prazosin , propranolol , plasma renin activity , aldosterone , tilt (camera) , medicine , endocrinology , hemodynamics , blood pressure , heart rate , essential hypertension , chemistry , renin–angiotensin system , antagonist , mechanical engineering , receptor , engineering
SUMMARY 1. To evaluate the haemodynamic and hormonal effects of prazosin, head‐up tilt was performed in 10 essential hypertensive patients, and these effects of prazosin on the tilt were compared with those of propranolol. The tilts were performed in control phase and the last days of treatment for two weeks with propranolol (90 mg/day) or prazosin (3–6 mg/day). 2. Each drug significantly lowered the mean blood pressure at rest, and also suppressed its rise on the tilt. Heart rates were significantly increased by the tilt in the control phase, in the propranolol phase and in the prazosin phase. Cardiac index was significantly reduced by the tilt from 2.66 (s.e.m. =0.22) 1/min per m 2 to 2.08 (s.e.m. =0.20) in the propranolol phase. However, there were not significant changes in other phases. Total peripheral resistance indices were significantly increased by the tilt in all three phases. Plasma renin activity and plasma aldosterone were significantly increased by the tilt from 2.14 (s.e.m. =0.47) ng/ml per h to 2.46 (s.e.m. =0.54) and from 50.6 (s.e.m. =12.9) pg/ml to 74.9 (s.e.m. =14.9) respectively, in the control phase. And they were also significantly increased from 1.06 (s.e.m. =0.29) to 1.65 (s.e.m. =0.45) and from 41.4 (s.e.m. =16.3) to 54.0 (s.e.m. =17.4) in the prazosin phase. There were no significant increases during the administration of propranolol. 3. We observed that prazosin did not alter heart rate and cardiac index, but suppressed the renin‐angiotensin system at rest. It is suggested that prazosin did not influence haemodynamic and hormonal responses to the tilt.