[Tissue chemoreceptors]

Intraarterial administration of acids or perfusion with solutions inducing acidosis in the small intestine tissue, increase the afferent impulsation in the splanchnic nerves as well as the arterial pressure in anesthetized cats. Threshold concentrations of lactic and carbonic acids don't exceed, at that, their normal contents in the blood and tissues. Similar data were obtained in perfusion of the small intestine with blood of a donor animal whose acid--alkaline balance (AAB) was altered. The tissue receptors were found to be more sensitive to the metabolic rather than respiratory acidosis, due to different alteration of of the intratissue pH. Sensitivity of the skeletal muscles' chemoreceptors proved somewhat lower as compared with the small intestine receptors. Nevertheless, the threshold shifts of the AAB parameters in the m. gastrocnemius perfusion developed within the normal range. The changes of minute volume of ventilation revealed the possibility of tissue receptors participation in the reflex control of respiration as well. The data on adequate sensitivity of the tissue receptors to terminal products of aerobic and anaerobic metabolism: carbonic and lactic acids, once more corroborate V. N. Tchernigosky's ideas of the tissue chemoreceptors as a special class of receptor structures providing the c.n.s. with necessary information on intensity of the tissue metabolism.