Effect of chronic insulin on cromakalim-induced relaxation in established streptozotocin-diabetic rat basilar artery.
Our goals were to determine whether the response of the rat isolated basilar artery to activation of ATP-sensitive potassium (KATP) channels is altered in diabetes mellitus, and to determine the effect of chronic insulin treatment on this response in established diabetic rats. The relaxation induced by cromakalim, an activator of KATP channels, was significantly weaker in insulin-untreated streptozotocin-induced diabetic rats than in the controls. This impairment was significantly improved following chronic administration of insulin. The relaxations induced by two Ca2+-activated K+-channel activators [1-ethyl-2-benzimidazolinone (1-EBIO) or 1, 3-dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one (NS1619)] were not significantly different between control and insulin-untreated diabetic rats. The sodium nitroprusside-induced relaxation was similar among the three groups (control, diabetic, and insulin-treated diabetic). These results suggest that: (a) the impaired cromakalim-induced relaxation seen in diabetic rats is not due to a nonspecific effect of diabetes mellitus on vasorelaxation, but at least partly to an effect on KATP channels, and (b) that this impaired relaxation can be restored by chronic insulin treatment.
Matsumoto
Takayuki
T
Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan.
Yoshiyama
Shintaro
S
Wakabayashi
Kentaro
K
Kobayashi
Tsuneo
T
Kamata
Katsuo
K
D000818:Animals; D001488:Basilar Artery / Q000187:drug effects* / Q000378:metabolism; D019806:Cromakalim / Q000494:pharmacology*; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D007328:Insulin / Q000008:administration & dosage*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D014664:Vasodilation / Q000187:drug effects* / Q000502:physiology
D007328:Insulin; D019806:Cromakalim