Effect of carbachol on radiosodium uptake by dispersed pancreatic acinar cells

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Abstract
The effects of carbachol on uptake of22Na by enzymatically dispersed rat pancreatic acinar cells were determined. Carbachol caused a slight but significant increase in uptake of22Na by the cells in the presence or absence of ouabain (10−3 M). A maximal response was obtained with 10−6 M carbachol. The effects of carbachol were blocked by 10−5 M atropine. Caerulein (10−7 M) also stimulated22Na uptake, while epinephrine (10−4 M) and substance P (10−7 M) did not. Carbachol did not stimulate22Na uptake in the absence of extracellular Ca, although Ca omission significantly clevated basal22Na uptake. The divalent cationophore A-23187 caused Ca-dependent22Na uptake at 20 μM concentration but not at 0.3 μM. These results, when considered with earlier reports by others, suggest that muscarinic receptor activation leads to an increase in permeability of the acinar cell membrane to Na, and that Ca may be second messenger for this effect.