Fluid and electrolyte secretion from the isolated, perfused submandibular and sublingual glands of the rat

Abstract

Isolated preparations of the rat submandibular gland secreted when perfused at a rate of 3 ml/min with physiological salt solutions containing glucose and either acetylcholine (10 −9 to 10 −4 M) or pilocarpine (10 −7 to 10 −3 M). The maximum secretory response was 250 μl g −1 min −1 with acetylcholine (10 −6 M) and 130 μl g −1 min −1 with pilocarpine (10 −6 M). Higher agonist concentrations usually resulted in smaller secretory responses. The response to continued stimulation showed a slow decline, although it was more sustained than with a similar preparation of the rabbit submandibular gland. The excretion curves for Na, K, Ca, Cl and HCO 3 evoked by the two parasympatho-mimetic agonists were similar to those reported from in-vivo experiments. Ouabain (10 −3 M), the substitution of Na by Li or the omission of K in the perfusion solution markedly inhibited the secretory response from the isolated, perfused-gland preparation. Partial substitution of the perfusate Na with choline caused only partial inhibition of secretion, but decreased Na and increased Ca and K concentrations in saliva. It is concluded that the perfused-gland preparation functions normally with respect to the secretion of fluid and electrolytes, and offers a suitable vehicle for investigation of the salivary secretory process. The sublingual gland secreted in response to pilocarpine. The maximum secretory rate was 130 μl g −1 min −1 and the saliva was poor in Na and Cl and rich in K, HCO 3 and Ca.