Effect of diazoxide, an ATP-dependent potassium-channel opener, on isolated aortae of normal and diabetic rats.
1. The effect of diazoxide on the potassium-induced contraction and its inhibitory effect on noradrenaline-induced contraction were studied in the isolated aortic rings of normal and streptozocin-treated diabetic rats. 2. Diazoxide relaxed potassium-induced contraction in normal and diabetic rat aortae. There was no statistically significant difference in the relaxing effect of diazoxide in these two groups of rats. Glibenclamide inhibited the relaxing effect of diazoxide in normal and diabetic rat aortae to the same extent. Pretreatment of tissues with diazoxide prevented the noradrenaline-induced contraction. This inhibitory effect significantly differed between normal and diabetic rats. 3. It is concluded that, in the rat aorta, the state of potassium channels and the potency of diazoxide to open these channels are not affected by experimental diabetes. The observed differences between the responses of normal and diabetic aortae to the inhibitory effect of diazoxide on noradrenaline-induced contraction can be attributed to a mechanism(s) other than potassium-channel opening by diazoxide, which might be modified in diabetes, or to different consequences after potassium-channel opening in diabetic tissues compared with normal tissues.
Mahmoudian
M
M
Department of Pharmacology, Iran University of Medical Sciences, Tehran. massoud@nrcgeb.ac.ir
Mirkhani
H
H
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001013:Aorta, Thoracic; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D003981:Diazoxide / Q000494:pharmacology*; D005905:Glyburide / Q000494:pharmacology; D007004:Hypoglycemic Agents / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects*; D051381:Rats
D000959:Antihypertensive Agents; D007004:Hypoglycemic Agents; D015221:Potassium Channels; D003981:Diazoxide; D011188:Potassium; D005905:Glyburide; D009638:Norepinephrine