Neurokinin induced inositol phosphate production in guinea pig bladder.

Abstract

To examine second messenger pathways involved in neurokinin induced bladder contractions. Neurokinin induced changes in inositol phosphate production and in adenylyl cyclase activity are measured in the guinea pig bladder. Substance P, substance P methyl ester, neurokinin A, and neurokinin B each increase [3H]-inositol phosphate production in the guinea pig bladder. Substance P (10(-6) M) increases [3H]-inositol trisphosphate levels within 30 sec. Substance P and neurokinin A have an additive effect on inositol phosphate production, however substance P (10(-5) M) or neurokinin A (10(-5) M) induced inositol phosphate production is less than that induced by carbachol (10(-5) M). Neurokinin B and to a lesser extent neurokinin A inhibit forskolin-activated adenylyl cyclase activity. These data are compatible with neurokinin-induced inositol phosphate production being coupled to increases in contractile force of the guinea pig urinary bladder, however more than one second messenger pathway may be involved.