Forskolin Changes the Relationship between Cytosolic Ca2+ and Contraction in Guinea Pig Ileum
The Korean Journal of Physiology and Pharmacology
;
: 189-194, 2009.
Article
Dans Anglais
| 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.
Texte intégral:
Disponible
Indice:
WPRIM (Pacifique occidental)
Sujet Principal:
Colforsine
/
Histamine
/
Guinée
/
Cytosol
/
Contrats
/
Guanosine triphosphate
/
Cochons d'Inde
/
Iléum
/
Muscles lisses
/
Tonus musculaire
Limites du sujet:
Animaux
Pays comme sujet:
Afrique
langue:
Anglais
Texte intégral:
The Korean Journal of Physiology and Pharmacology
Année:
2009
Type:
Article
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