The effects of calcium and magnesium ions, temperature and repetitive stimulation on inhibitory junctional transmission in smooth muscle of guinea-pig small intestine.

摘要: Abstract 1 The effects of calcium and magnesium ions temperature on the peak amplitude nonadrenergic, noncholinergic inhibitory junction potential, evoked by a single stimulus, or paired transmural stimuli, were examined in circular muscle guinea-pig small intestine. 2 potential (i.j.p.) could be decreased lowering external concentration raising (at 25°C). 3 At 25°C, second pair i.j.ps was larger than first at short intervals (<0.2 s), but smaller (0.2 to 20 s). Enhancement (test) response decayed exponentially with time constant 87 ms. Depression test i.j.p. maximal 0.4 s then recovered 11 s. 4 In low high solution, depression without any change rate recovery from depression. 5 Despite slow after conditioning response, transmitter output maintained during low-frequency repetitive stimulation. 6 increased as raised 35°C (Q10 = 1.5). 7 contrast neuromuscular junction, raised. for most stimulus (1 s). 8 results suggest that replenishment store is sensitive both stimulation.