IP3 and GTP gamma S cause contraction of permeabilised guinea pig ileum longitudinal smooth muscle via distinct mechanisms.

Abstract

IP3 is well established as being a mediator of calcium release from intracellular calcium stores. GTPγS (a stable analogue of GTP frequently used to activate GTP-binding proteins), however, has also been reported to cause calcium release and contractions in permeabilised rabbit main pulmonary artery (Kobayashi et al., 1988). We have previously reported (Allen & Carpenter, 1989) that inositol 1,4,5-trisphosphate (IP3) causes a contraction of saponin-permeabilised guinea-pig ileum longitudinal smooth muscle. Here we demonstrate that GTPγS also causes a contraction of permeabilised ileum longitudinal smooth muscle, though via a mechanism distinct from that of IP3.KeywordsCalcium ReleaseUpward ShiftMaximal ContractionSmooth Muscle LayerRelax SolutionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.