Pregnancy: Its Effects on Blood Pressure, Heart Rate and Sympatho-Adrenal Activity in Spontaneously Hypertensive Rats 1

Summary Blood pressure, heart rate and plasma catecholamine levels were compared in non-pregnant and term-pregnant SP-SHR, SHR, and WKY female rats. Rats were anesthetized with halothane and the ventral caudal artery was cannulated. The pregnancy success rate for hypertensive females (SP-SHR and SHR) was significantly lower than for WKY females (P < 0.01). Pregnancy was associated with an increase in heart rate for females of each strain (P < 0.05). No differences were observed between pregnant and control females of the three strains with regard to blood pressure or levels of circulating catecholamines. These findings indicate that pregnancy is not attended by further increases in blood pressure or sympatho-adrenal activity in SP-SHR, SHR, or WKY females. Additional studies of SHR females may provide an experimental model for the evaluation and treatment of complications arising during pregnancy in patients with chronic hypertension.