IP3 and GTPγS Cause Contraction of Permeabilised Guinea Pig Ileum Longitudinal Smooth Muscle Via Distinct Mechanisms
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 Release Upward Shift Maximal Contraction Smooth Muscle Layer Relax Solution
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