Sodium nitroprusside relaxes goat coronary artery through activation of calcium-dependent K+ channels.
Indian J Exp Biol
;
2005 Apr; 43(4): 324-9
Artigo
em Inglês
| IMSEAR
| ID: sea-59079
ABSTRACT
In the present investigation we have examined the hypothesis that calcium-dependent K+ channels (K(Ca)) are involved in the sodium nitroprusside (SNP)-induced vasodilatation of goat coronary artery. SNP (10(-9)-3 x 10(-6) M), added cumulatively, relaxed K+ (30 mM)-contracted coronary artery ring segments in a concentration-dependent manner with an EC50 of 1.32 x 10(-7) M (95% CL, 0.93-1.86 x 10(-7) M; n = 21). K(Ca) blocker, tetraethyl ammonium (1 mM) caused a rightward shift in the concentration-response curve of SNP with a corresponding increase in EC50 (1.62 x 10(-6) M; 95% CL, 0.44-6.02 x 10(-6) M, n = 4) of nitro vasodilator. Lowering of extra cellular Ca2+ in the physiological saline solution to 1/4 of normal selectively attenuated the vasorelaxant response of SNP, thereby causing an increase in its EC50 (2.4 x 10(-6) M; 95% CL, 1.23-4.68 x 10(-6) M, n = 4). Exposure of the tissues to high K+ (80 mM) solution, a protocol adopted to reduce the K+ gradient across the cell membrane, markedly inhibited the coronary artery relaxations induced by SNP (EC50, 2.54 x 10(-6) M; 95% CL, 1.31-4.91 x 10(-6) M, n = 4), when compared with tissues contracted with low K+ (30 mM) solution (EC50 7.9 x 10(-8); 95% CL, 4.4 x 10(-8)-1.44 x 10(-7) M, n = 6). The results suggested that a major component of SNP-induced relaxation of goat coronary artery was mediated by K(Ca) channels.
Texto completo:
DisponíveL
Índice:
IMSEAR (Sudeste Asiático)
Assunto principal:
Cloreto de Potássio
/
Vasodilatação
/
Cabras
/
Nitroprussiato
/
Cloretos
/
Cálcio
/
Compostos de Bário
/
Vasos Coronários
/
Doadores de Óxido Nítrico
/
Canais de Potássio Cálcio-Ativados
Idioma:
Inglês
Revista:
Indian J Exp Biol
Ano de publicação:
2005
Tipo de documento:
Artigo
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