Blood pressure in streptozotocin-treated Brattleboro and Long-Evans rats

The diabetogenic agent streptozotocin (STZ) was injected intraperitoneally in Long-Evans and arginine vasopressin (AVP)-deficient Brattleboro rats. Twenty-eight days later both strains had a bradycardia and systolic hypotension; STZ-treated Brattleboro rats also had diastolic hypotension. The vasopressin (V1-receptor) antagonist, d(CH2)5[Tyr(Et)]DAVP, had no effect on resting blood pressure (BP) or heart rate (HR) in either strain of rat, indicating the relative maintenance of diastolic BP in STZ-treated Long-Evans rats was not dependent on acute vascular actions of AVP. Captopril caused a modest hypotension in all groups of rats, indicating that BP was not differentially dependent on the renin-angiotensin system in the different groups. In the presence of captopril and the ganglion blocker, pentolinium tartrate, the AVP-mediated recovery in BP was impaired in STZ-treated Long-Evans rats. During administration of d(CH2)5[Tyr(Et)]DAVP and pentolinium, the angiotensin II (ANG II)-mediated BP recovery was smaller in both groups of STZ-treated rats, indicating that this abnormality was not likely to be caused by inhibition of renin release by AVP. The abnormalities in ANG II- and AVP-mediated recovery were prevented by insulin treatment.