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Forskolin Changes the Relationship between Cytosolic Ca2+ and Contraction in Guinea Pig Ileum
The Korean Journal of Physiology and Pharmacology ; : 189-194, 2009.
Artículo en Inglés | WPRIM | ID: wpr-728736
ABSTRACT
This study was designed to clarify the mechanism of the inhibitory effect of forskolin on contraction, cytosolic Ca2+ level ([Ca2+]i), and Ca2+ sensitivity in guinea pig ileum. Forskolin (0.1 nM~10 micrometer) inhibited high K+ (25 mM and 40 mM)- or histamine (3 micrometer)-evoked contractions in a concentration-dependent manner. Histamine-evoked contractions were more sensitive to forskolin than high K+-evoked contractions. Spontaneous changes in [Ca2+]i and contractions were inhibited by forskolin (1 micrometer) without changing the resting [Ca2+]i. Forskoln (10 micrometer) inhibited muscle tension more strongly than [Ca2+]i stimulated by high K+, and thus shifted the [Ca2+]i-tension relationship to the lower-right. In histamine-stimulated contractions, forskolin (1 micrometer) inhibited both [Ca2+]i and muscle tension without changing the [Ca2+]i-tension relationship. In alpha-toxin-permeabilized tissues, forskolin (10 micrometer) inhibited the 0.3 micrometer Ca2+-evoked contractions in the presence of 0.1 mM GTP, but showed no effect on the Ca2+-tension relationship. We conclude that forskolin inhibits smooth muscle contractions by the following two mechanisms a decrease in Ca2+ sensitivity of contractile elements in high K+-stimulated muscle and a decrease in [Ca2+]i in histamine-stimulated muscle.
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Texto completo: Disponible Índice: WPRIM (Pacífico Occidental) Asunto principal: Colforsina / Histamina / Guinea / Citosol / Contratos / Guanosina Trifosfato / Cobayas / Íleon / Músculo Liso / Tono Muscular Límite: Animales País/Región como asunto: Africa Idioma: Inglés Revista: The Korean Journal of Physiology and Pharmacology Año: 2009 Tipo del documento: Artículo

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Texto completo: Disponible Índice: WPRIM (Pacífico Occidental) Asunto principal: Colforsina / Histamina / Guinea / Citosol / Contratos / Guanosina Trifosfato / Cobayas / Íleon / Músculo Liso / Tono Muscular Límite: Animales País/Región como asunto: Africa Idioma: Inglés Revista: The Korean Journal of Physiology and Pharmacology Año: 2009 Tipo del documento: Artículo