Central imidazoline and angiotensin II receptors in cardiovascular responses to chronic cold exposure in rats

Abstract

(1) Chronic exposure to cold (5°C) induced hypertension in rats within one week. (2) Chronic central administration of an I 1 imidazoline receptor agonist, rilmenidine, prevented the development of cold-induced hypertension (CIH). (3) Plasma renin activity and urine norepinephrine output were significantly decreased by central administration of rilmenidine during cold acclimation. (4) Pressor response to central injection of angiotensin II (AII) was inhibited by rilmenidine. (5) Thus, activation of central I1 receptors could prevent the development of CIH and this may be related to inhibition of pressor effect of central AII. This finding reveals possible relationship between central I 1 and AII receptors in cardiovascular responses to chronic cold exposure.