M3 muscarinic receptors mediate an increase in both inositol trisphosphate production and cyclic AMP formation in dog iris sphincter smooth muscle.
J Ocul Pharmacol
; 10(1): 137-47, 1994.
Article
en En
| MEDLINE
| ID: mdl-8207321
ABSTRACT
Pharmacological studies on pirenzepine (PZ), 4-diphenylacetoxy-N-methyl-piperidine (4-DAMP) and AFDX-116 antagonism of carbachol (CCh)-induced contraction, inositol trisphosphate (IP3) production and cAMP formation revealed the involvement of M3 receptors in these responses. The PA2 values for PZ and 4-DAMP antagonism to CCh-induced contraction were 7.1 and 9.0, respectively, and AFDX-116 had no effect on these responses. Further, 4-DAMP was a much more potent inhibitor than PZ of CCh-stimulation of IP3 production and cAMP formation. Both L-type calcium channel blockers, which inhibit Ca2+ influx, and BAPTA, an intracellular calcium chelator, inhibited these biochemical and pharmacological responses due to CCh. It is concluded that both intracellular and extracellular Ca2+ mobilization are involved in muscarinic stimulation of cAMP production, and that M3 receptors are coupled to the activation of both phospholipase C and adenylate cyclase in this tissue. The data presented here are consistent with previous work that stimulation of muscarinic receptors in dog iris sphincter with CCh (> 5 microM) increases intracellular cAMP levels.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Inositol 1,4,5-Trifosfato
/
Iris
/
Receptores Muscarínicos
/
AMP Cíclico
/
Músculo Liso
Límite:
Animals
Idioma:
En
Revista:
J Ocul Pharmacol
Asunto de la revista:
FARMACOLOGIA
/
OFTALMOLOGIA
Año:
1994
Tipo del documento:
Article