Effect of prolonged administration of clonidine to spontaneously hypertensive rats on blood pressure, cerebral norpinephrine content and angiographic finding in the kidney.
1. The effects of clonidine on blood pressure, cerebral norepinephrine content and vascular structures of the kidneys were investigated in 21 SHR. Although the body weight was not affected by long term clonidine treatment up to 36 weeks, the syatolic blood pressure was significantly reduced. The reduction of the blood pressure was already obvious after 1 week administration of clonidine but the effect was  more prominent after long term treatment of 30 weeks or longer. 2. The cerebral norepinephrine content was significantly lower in SHR, regardless of with or without clonidine treatment, than in the control Wistar rats. Although the cerebral norepinephrine content was slightly increased following clonidine treatment SHR, the increase was not statistically significant. 3. Angiographic study of the kidneys revealed a poor opacification of the blood vessels and glomeruli in SHR compared with the control Wistar rats. There was no difference in the sizes of the arcuate and interlobular arteries in SHR and the control Wistar rats, although the medial muscular hypertrophy of the arteries was slightly more prominent in the SHR histologically. The more prominent in the SHR histologically. The angiographic and histologic findings of the renal arteries were not altered following long term clonidine treatment. A possibility was considered that the renal arterioles are mainly functionally affected in SHR.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D003000:Clonidine / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006973:Hypertension / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000378:metabolism; D007668:Kidney / Q000098:blood supply; D009638:Norepinephrine / Q000378:metabolism*; D009929:Organ Size; D011859:Radiography; D051381:Rats; D012077:Renal Artery / Q000000981:diagnostic imaging*
D003000:Clonidine; D009638:Norepinephrine