Effects of long-term administration of propyldazine on blood pressure and counter-regulatory systems in conscious hypertensive dogs.
The counter-regulatory effects in response to blood pressure reduction by propyldazine were studied in conscious dogs with bilateral cellophane perinephritis hypertension. During a 22-day period of chronic treatment, the initial increase in heart rate, plasma renin activity, angiotensin II, aldosterone, and vasopressin, which indicate counter-regulation to the drug induced decrease in blood pressure, vanished. On the fifth day of treatment another, presumably cellular mechanism, had taken over the restitution of blood pressure and thereby led to tolerance towards the action of further propyldazine administration. Seven days after the end of chronic treatment a renewed propyldazine administration did not produce the same effects as obtained with the first administration; after 28 days the hypotensive effect of propyldazine was identical to the one observed before treatment.
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects; D004285:Dogs; D004361:Drug Tolerance; D005260:Female; D006977:Hypertension, Renal / Q000188:drug therapy*; D011724:Pyridazines / Q000494:pharmacology / Q000627:therapeutic use*; D012084:Renin-Angiotensin System / Q000187:drug effects; D013564:Sympathetic Nervous System / Q000187:drug effects; D014667:Vasopressins / Q000097:blood
D000959:Antihypertensive Agents; D011724:Pyridazines; D014667:Vasopressins; C009978:propildazine