Calcium binding by rat submaxillary glands in vitro

Histamine and calcium secretion in the submandibular gland of the cat evoked by two types of stimulation

The aim of this work was to compare the pools of histamine and calcium in the submandibular gland of the cat during two kinds of stimulation of the gland. Submandibular glands of the cat were stimulated electrically (chorda tympani nerve) and by close arterial infusion of pilocarpine. Each stimulation was adjusted in such a way as to obtain a near maximal secretory response. Concentrations of histamine and calcium were measured in nonstimulated and stimulated glands, in saliva, secreted during stimulation and in the venous outflow from the gland before and during the stimulation. The experiments showed that: pilocarpine stimulation lowered the histamine concentration in the gland more than electrical stimulation of the chorda tympani nerve. Calcium stores in the gland were depleted to the same extent by each type of stimulation. the concentration of histamine and calcium in the saliva produced by close arterial pilocarpine infusion was significantly higher than in the saliva secreted during nerve stimulation. histamine and calcium concentrations were higher in the venous outflow from stimulated glands than before stimulation. The results indicate a close relationship between histamine and calcium in salivary secretion, although the origins of the two substances are different.

Salivary electrolyte changes during the normal menstrual cycle

Daily samples of parotid and submaxillary saliva were collected from eight females during a complete menstrual cycle. Findings revealed significant electrolyte changes in the submaxillary saliva. Comparison of menstrual and midcycle concentrations of calcium and sodium demonstrated a notable decrease in calcium and sodium at midcycle, whereas potassium levels increased significantly. Changes were attributed to a probable hormonal effect on salivary composition.

CALCIUM ACCUMULATION AND RESPIRATORY ACTIVITY OF THE SMALL INTESTINE OF THE RAT

The possible dependence of calcium accumulation upon respiratory activity of the rat small intestine has been investigated in vitro. The oxygen consumption of this tissue was relatively insensitive to the concentration of calcium in the medium; and the accumulation of radioactive calcium was greatly dependent upon ambient calcium concentration. At low concentrations of the medium the ratio of tissue calcium to that in the medium greatly exceeded unity, indicating an accumulation of this ion against a concentration gradient. However, this effect was also seen when the tissues were incubated in a gas phase of nitrogen instead of oxygen, demonstrating the lack of dependence of this process on tissue respiration. The rate at which calcium accumulated at 0° also suggests that the accumulation of calcium by the small intestine is not a metabolically controlled process but rather is a binding phenomenon similar to that reported for salivary gland of the rat.