Losartan Normalizes Endothelium-Derived Hyperpolarizing Factor–Mediated Relaxation by Activating Ca2+-Activated K+ Channels in Mesenteric Artery From Type 2 Diabetic GK Rat

Journal of Pharmacological Sciences

Keiko Ishida¹  Kumiko Taguchi¹  Katsuo Kamata¹  Takayuki Matsumoto¹  Tsuneo Kobayashi¹ 

[1] Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Japan

关键词: angiotensin receptor antagonist;    diabetes;    endothelium-derived hyperpolarizing factor (EDHF);    GK rat;    potassium channel;   

DOI  :  10.1254/jphs.09308FP

学科分类：药学

来源: Nihon Yakuri Gakkai Henshuubu / Japanese Pharmacological Society

【 摘 要 】

References(56)Cited-By(11)Ca2+-activated K+ (KCa) channels are important for endothelium-derived hyperpolarizing factor (EDHF) signaling. Since treatment with angiotensin II receptor blockers (ARBs) improves vasculopathies in type 2 diabetic patients, we asked whether the EDHF-type relaxation and its associated KCa channels [small (SKCa)–, intermediate (IKCa)–, and large (BKCa)–conductance channels] are abnormal in mesenteric arteries isolated from Goto-Kakizaki (GK) rats at the chronic stage of type 2 diabetes (34 – 38 weeks) and whether an ARBs (losartan, 25 mg · kg−1 · day−1 for 2 weeks) might correct these abnormalities. Although the acetylcholine chloride–induced EDHF-type relaxation in mesenteric arteries from GK rats was reduced versus the Wistar controls, it was significantly restored by losartan treatment. The SKCa-blocker apamin or the IKCa-blocker 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34) inhibited such relaxations in the losartan-treated or -untreated Wistar groups and in the losartan-treated GK group, but not in the losartan-untreated GK group. The BKCa-blocker iberiotoxin had a significant inhibitory effect in only one of these groups, the losartan-treated GK. The relaxations induced by the SKCa/IKCa activator NS309 and the BKCa activator NS1619, which were impaired in GK rats, were normalized by losartan treatment. We conclude that losartan improves EDHF-type relaxation in GK rats at least partly by normalizing SKCa/IKCa activities and increasing BKCa activity.

【 授权许可】

Unknown