Respiration during hypothermia: effect of rewarming intermediate areas of ventral medulla

Abstract

MILLHORN. Respiration during hypothermia: effect of rewarm-ing intermediate areas of ventral medulla. J. Appl. Physiol. 59(5): 1423-1427,19&S.-We studied respiration (phrenic nerve activity) during progressive hypothermia to as low as XU”C in five anesthetized, paralyzed, glomectomized, and vagotomized cats. PCO ~ was maintained at a constant level throughout the experiments. We confirmed the results of a previous study (J. P. Kiley, F. L. Eldridge, and D. E. Millhorn, J. A&. Physiol. 58: 295-312, 1985) in which respiratory minute output de-creased progressively with cooling and respiratory frequency decreased markedly. In addition we show that focal rewarming to normal temperature (37.5”C) of the structures in the inter-mediate areas on the ventral surface of the medulla resulted in a significant reversal of the depressed respiratory minute activ-ity observed with hypothermia. Respiratory frequency, how