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

(1) Chronic exposure to cold (5 degreesC) induced hypertension in rats with in one week. (2) Chronic central administration of an I-1 imidazoline recep tor agonist, rilmenidine, prevented the development of cold-induced hyperte nsion (CIH). (3) Plasma renin activity and urine norepinephrine output were significantly decreased by central administration of rilmenidine during co ld acclimation. (4) Pressor response to central injection of angiotensin II (AII) was inhibited by rilmenidine. (5) Thus, activation of central I1 rec eptors could prevent the development of CIH and this may be related to inhi bition of pressor effect of central AII. This finding reveals possible rela tionship between central I-1 and AII receptors in cardiovascular responses to chronic cold exposure. (C) 2001 Elsevier Science Ltd. All rights reserve d.