Some effects of hypertonic solution on the properties of spontaneous transmitter release in the hypogastric ganglia of guinea-pigs.

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Abstract
The effects of hypertonic solutions on spontaneous transmitter release at synapses in the hypogastric ganglia of guinea pigs were studied using intracellular recording techniques. Hypertonic solutions caused a marked hyperpolarization of the ganglion cells and this was accompanied by an increase in both the threshold and input resistance of these cells. The frequency of spontaneous quantal release depended exponentially on the tonicity of the bathing solution with a 50% increase in tonicity producing a 7- to 9-fold increase in the frequency of release. Hypertonic solutions increased the degree of bursting within the spontaneous process so that the proportion of multiquantal spontaneous potentials was increased in such solutions. Two different models, the charge-screening model (Van der Kloot and Kita, 1973) and the Ca-increase model (Shimoni et al., 1977), for the mechanism underlying the effects of hypertonic solution were considered.