Chloride channel activity of vascular smooth muscle in the spontaneous hypertensive rats.
To characterize the activity of the Ca2+-activated Cl- channels in vascular smooth muscle (VSM) of the spontaneous hypertensive rats (SHR), the isolated mesenteric vascular beds and tail artery strips were preparated from SHR and Wistar rats aged 7-8 weeks. The changes in contractile response to norepinphrine (NE) were taken as an index of vascular mortion. Results showed that the contractile responses of mesenteric arteries and tail arteries to NE in SHR were significantly greater than that in Wistar rats. The inhibition magnitude of the contractile response by Ca2+-activated Cl- channel blocker, niflumic acid in SHR was significantly less than that in Wistar rats. Decreasing the extracellular Cl- concentration increased the contractile response to NE significantly, but the amplitude of enhanced contractile response in SHR was greater than that in Wistar rats. It can be concluded that NE-induced contraction was enhanced in SHR, which is partly due to an increase in Cl- efflux through the Ca2+-activated Cl- channels. The chloride channel activity may be increased in association with the elevation of blood pressure.
Wang
Zhen
Z
Institute of Physiology, School of Medicine, Shandong University, Jinan, Shandong Province, 250000 People's Republic of China.
Chai
Qiang
Q
Liu
Zhixiang
Z
Liu
Dexiang
D
Chen
Lianbi
L
D000818:Animals; D001158:Arteries / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000494:pharmacology; D018118:Chloride Channels / Q000378:metabolism*; D002712:Chlorides / Q000037:antagonists & inhibitors / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D006973:Hypertension / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D009544:Niflumic Acid / Q000008:administration & dosage / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D009994:Osmolar Concentration; D051381:Rats; D011918:Rats, Inbred SHR / Q000378:metabolism*; D017208:Rats, Wistar; D013623:Tail / Q000098:blood supply; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D002121:Calcium Channel Blockers; D018118:Chloride Channels; D002712:Chlorides; D014662:Vasoconstrictor Agents; D009544:Niflumic Acid; D002118:Calcium; D009638:Norepinephrine