Inhibition of membrane L-type calcium channel activity and intracellular calcium concentration by 24R, 25-dihydroxyvitamin D3 in vascular smooth muscle.
Pharmacological doses of 24R,25-dihydroxyvitamin D3 (24,25D3) inhibited both phasic and tonic contraction of Sprague-Dawley (SD) rat tail artery helical strips induced by KCl, norepinephrine (NE), and arginine vasopressin (AVP) in organ-bath studies. 24,25D3 also decreased the tension dependent on external calcium influx induced by KCl, AVP, and NE and the tension dependent on internal calcium release from intracellular calcium stores induced by NE. In vascular smooth muscle cells isolated from SD rat tail artery, 24,25D3 reduced membrane L-type calcium channel current and the increment of intracellular calcium concentration induced by KCl. It is suggested that 24,25D3 directly relaxed precontracted SD rat-tail artery by its inhibitory effect on plasma membrane and intracellular organelle calcium channels.
Department of Physiology, Faculty of Medicine, University of Alberta, Edmonton, Canada.
J J
JJ
Shan
B
B
Li
N
N
Taniguchi
P K
PK
Pang
D015650:24,25-Dihydroxyvitamin D 3 / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects* / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D015650:24,25-Dihydroxyvitamin D 3; D002118:Calcium; D009638:Norepinephrine