EFFECTS OF PROLONGED TREATMENT WITH BETA-ADRENOCEPTOR ANTAGONIST, CARTEOLOL ON SYSTEMIC AND REGIONAL HEMODYNAMICS IN STROKE-PRONE SPONTANEOUSLY HYPERTENSIVE RATS

The present study was designed to determine the regional hemodynamic effects of prolonged beta-adrenergic receptor inhibition in conscious stroke-prone spontaneously hypertensive rats (SHRSP) using a radioactive microsphere method. When the regional blood flow was compared between 10 and 30 weeks of age, the age-related changes in organ blood flow were observed in several organs, i.e., the reduction of flow rate in kidney, adrenal gland and intestines. The reduction of flow rate in these organs contributes strongly to the age-related rise of total peripheral resistance. Carteolol, a beta-adrenoceptor antagonist, was given at a dose of 10 mg/kg/d from 10 to 30 weeks of age. These animals gained more weight than the untreated control SHRSPs, and heart rate was reduced significantly. Blood pressure was not affected. However, the prolonged treatment with carteolol prevented the age-related reduction of the blood flow rate in the kidney, adrenal gland and intestines. Thus, our findings indicate that carteolol had appreciable and beneficial effects on the maintenance of flow rates in the above organs of SHRSP without any change in blood pressure.