Potentiation of stretch-induced tone in the rabbit facial vein by an isoquinoline derivative, LOE 908.
The rabbit facial vein exhibits extracellular Ca2+- and temperature-dependent spontaneous myogenic tone in response to stretch. The present study aimed to elucidate pharmacological characteristics of Ca2+ entry mechanisms responsible for the stretch-induced tension development of the rabbit facial vein. Ca2+- and temperature-sensitive vascular tone in response to stretch was refractory to L-type Ca2+ channel blockers such as nifedipine and diltiazem but was abolished by papaverine or SK&F 96365 which blocks both receptor- and store-operated Ca2+ channels. Interestingly, LOE 908, another type of voltage-independent Ca2+-permeable channel blocker, showed augmentation of the stretch-induced vascular tone instead of inhibition. Potentiation by LOE 908 of stretch-induced vascular tone was also extracellular Ca2+-dependent and counteracted by SK&F 96365. Membrane stretch-activated Ca2+ channels in the rabbit facial vein smooth muscle cells may have a unique characteristic that their opening is stimulated by LOE 908 and thus is distinguishable from other voltage-independent Ca2+-permeable channels.
Tanaka
Y
Y
Department of Pharmacology, Toho University School of Pharmaceutical Sciences, Chiba, Japan.
Someya
S
S
Tanaka
H
H
Tsuru
H
H
Shigenobu
K
K
D000081:Acetamides / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D005145:Face / Q000098:blood supply*; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects; D007546:Isoquinolines / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009129:Muscle Tonus / Q000187:drug effects* / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D011817:Rabbits; D012026:Reflex, Stretch / Q000187:drug effects* / Q000502:physiology; D013696:Temperature; D014680:Veins / Q000187:drug effects / Q000502:physiology
D000081:Acetamides; D007093:Imidazoles; D007473:Ion Channels; D007546:Isoquinolines; C081356:LOE 908; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole; D002118:Calcium