Effects of valinomycin on calcium mobilization in vascular smooth muscle cells induced by angiotensin II.
The effect of the specific potassium (K+) ionophore valinomycin on increase in intracellular calcium concentration [( Ca2+]i) was studied in vascular smooth muscle cells (VSMC). Valinomycin at more than 10(-9) M dose-dependently suppressed phasic increase in [Ca2+]i in VSMC induced by angiotensin II (AII) in both control and Ca2+-free solution, indicating that it suppressed the release of Ca2+ from intracellular Ca2+ stores. Nicorandil and cromakalim, which are both K+ channel openers, also suppressed the increases in [Ca2+]i induced by AII in the Ca2+ free solution. However, valinomycin did not suppress AII-induced production of inositol 1,4,5-trisphosphate (IP3), which is known to mediate the release of Ca2+. These results indicate that decrease of intracellular K+ induced by valinomycin suppressed the release of Ca2+ from intracellular Ca2+ stores induced by IP3.
Koh
E
E
Department of Geriatric Medicine, Osaka University Medical School, Japan.
Morimoto
S
S
Takamoto
S
S
Morita
R
R
Kim
S
S
Hironaka
T
T
Nabata
T
T
Onishi
T
T
Ogihara
T
T
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001578:Benzopyrans / Q000494:pharmacology; D002118:Calcium / Q000096:biosynthesis / Q000502:physiology*; D019806:Cromakalim; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D004987:Ethers / Q000494:pharmacology; D005260:Female; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000096:biosynthesis; D015759:Ionomycin; D007476:Ionophores / Q000494:pharmacology; D008985:Monensin / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D009536:Niacinamide / Q000031:analogs & derivatives / Q000494:pharmacology; D020108:Nicorandil; D011758:Pyrroles / Q000494:pharmacology; D051381:Rats; D014634:Valinomycin / Q000494:pharmacology*
D001578:Benzopyrans; D004987:Ethers; D007295:Inositol Phosphates; D007476:Ionophores; D011758:Pyrroles; D019806:Cromakalim; D000804:Angiotensin II; D014634:Valinomycin; D009536:Niacinamide; D020108:Nicorandil; D015759:Ionomycin; D015544:Inositol 1,4,5-Trisphosphate; D008985:Monensin; D002118:Calcium