| Popis: |
In the dog salivary secretion, elicited by continuous administration of pilocarpine, is decreased by intravenous injection of sodium bicarbonate, of sodium carbonate, or of sodium hydroxide. The decrease in secretion produced by sodium bicarbonate is greater the larger the dose, and is obtained in like degree whether the bicarbonate is injected in isotonic or in hypertonic solution. The effect of sodium carbonate upon secretion is greater than that of sodium bicarbonate, and the effect of sodium hydroxide greater than that of either of the other two substances. Intravenously administered sodium bicarbonate prevents almost completely the augmenting effect upon salivary secretion of a ten minute period of re-breathing, though carbon dioxide accumulated in the re-breathing tank to the same extent as in a similar period of re-breathing without sodium bicarbonate administration. Each of the three alkaline agents increases submaxillary blood-volume flow as a rule. Sodium chloride or sodium sulphate intravenously administered in isotonic solution increases submaxillary secretion and blood-volume flow. Both agents administered in hypertonic solution decrease salivary secretion but increase more markedly submaxillary blood-volume flow. The effect upon secretion of isotonic and hypertonic solutions of sodium chloride and sodium sulphate appears to be due to the increase in blood-flow and to their influence upon the fluid available to the gland cells by withdrawal of water from the tissues. The described effects of the alkaline substances and neutral salts were obtained with the chorda tympani cut, and were not affected by cutting also the vago-sympathetic. It is suggested that the effects upon salivary secretion of intravenous injection of sodium bicarbonate, sodium carbonate, and sodium hydroxide are due mainly to changes in acid base equilibrium, in which the hydrogen-ion concentration of the interior of the cell may be a major factor. A comparison of the effects of carbon dioxide, of sodium bicarbonate, and of sodium carbonate on pulmonary ventilation, mean blood-pressure, and salivary secretion is made. |
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