Title: Effect of an oral contraceptive agent on blood pressure response to renin. (34640).

POPLINE Document Number: 702140

Author(s):

Douglas BH
Hull RP
Langford HG

Source citation:

Proceedings of the Society for Experimental Biology and Medicine, 1970 Apr;133:1142-1144.

Abstract:

This study attempted to determine why an occasional patient develops hypertension that appears to be related to the use of oral contraceptives. Changes in the renin-angiotension-aldosterone system have been blamed. Renin, an enzyme from the kidney, acts on renin substrate, a plasma protein, to release angiotensin, a powerful vasoconstrictor and stimulator of aldosterone secretion. The concentration of renin substrate has been shown to be increased by estrogen. In this study 20 Holtzman albino female rats were treated with norethynodrel with mestranol (Enovid R), given in their diet at .1 mg/kg/day. 20 other rats received 1 mg/kg/day. There were 20 controls. After 3 weeks of therapy, cannula were placed in the femoral arteries and jugular veins. Angiotensin, .12, .25, and .50 mg/kg, was administered iv and blood pressure response recorded in 10 animals from each group. Blood pressure response to renin was determined on the remaining animals. (Amounts of renin giving a response approximately equal to the 3 dosages of angiotensin were used.) Rats given 1 mg/kg/day of Enovid had a significant decrease in blood pressure (p less than .01) to the .5 mcg angiotensin. The .1 mg of Enovid had no effect on blood pressure. All doses of renin produced an increase in blood pre ssure response in rats treated with 1 mg/kg/day of Enovid (p less than .01). Those treated with .1 mg/kg/day had slightly decreased blood pressure response. Angiotensin responsiveness was shown to be decreased when renin was increased. Data indicate that renin-substrate is rate-limiting in vivo in blood pressure response to exogenous renin. However, renin levels may not give a true guide to angiotensin production. As angiotensin responsiveness can be reduced by oral contraceptive agents, determination of angiotensin levels and responsiveness is necessary before the role of changes in the renin-angiotensin system in the genesis of oral contraceptive hypertension can be evaluated.

Keywords:

Animals, Laboratory
Hypertension
Renin-Angiotensin-Aldosterone Effects
Contraceptive Agents, Side Effects
Norethynodrel
Mestranol
Blood Pressure
Women
Side Effects
Oral Contraceptives, Combined
Clinical Research
Research Methodology
Vascular Diseases
Diseases
Homeostasis
Physiology
Biology
Contraceptive Agents
Contraception
Family Planning
Contraceptive Agents, Progestin
Contraceptive Agents, Female
Contraceptive Agents, Estrogen
Hemic System
Demographic Factors
Population
Treatment
Oral Contraceptives
Contraceptive Methods