Potentiation by neurotensin of carbachol-induced tension development in beta-escin-skinned smooth muscle of guinea-pig ileum.
Effect of neurotensin (NT) on carbachol(CCh)-induced tension development due to Ca2+ release from intracellular stores was investigated in beta-escin-skinned smooth muscle of guinea-pig ileum. NT (10 nM) increased the tension development in response to CCh. NT also increased the tension response to caffeine, another store-Ca2+ releaser. NT did not exert such an effect in pertusis toxin (PTX)-treated preparations. Treatment with isoprenaline to elevate endogenous cyclic AMP levels or with dibutyryl cyclic AMP did not affect the effect of NT. A nonpeptide NT antagonist, SR 48692, failed to block the effect of NT. NT shifted the pCa-tension relationship in the lower direction of Ca2+ concentration. NT was incapable of releasing Ca2+ from intracellular stores. The results suggest that NT may cause an increase in Ca2+ sensitivity of contractile elements to potentiate the CCh-induced tension development due to release of stored Ca2+ and that the effect is mediated by SR 48692-insensitive NT receptors linked to a PTX-sensitive G protein which works with no relation to a change in cytosolic cyclic AMP levels.
Unno
T
T
Department of Veterinary Medicine, Faculty of Agriculture, Gifu University, Japan.
Shingu
H
H
Isogai
M
M
Komori
S
S
Ohashi
H
H
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002110:Caffeine / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002217:Carbachol / Q000494:pharmacology*; D004357:Drug Synergism; D004928:Escin; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects*; D066298:In Vitro Techniques; D007476:Ionophores / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D009496:Neurotensin / Q000494:pharmacology*; D011720:Pyrazoles / Q000494:pharmacology; D011804:Quinolines / Q000494:pharmacology; D018028:Receptors, Neurotensin / Q000037:antagonists & inhibitors; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D007476:Ionophores; D011720:Pyrazoles; D011804:Quinolines; D018028:Receptors, Neurotensin; D010566:Virulence Factors, Bordetella; C079087:SR 48692; D000001:Calcimycin; D009496:Neurotensin; D002110:Caffeine; D003994:Bucladesine; D004928:Escin; D002217:Carbachol; D007545:Isoproterenol; D002118:Calcium