Control of breathing and ventilatory acclimatization to hypoxia in deer mice native to high altitudes

Abstract

Our results suggest that highland deer mice have evolved high rates of alveolar ventilation and respiratory O uptake without the significant enlargement of the carotid bodies that is typical of VAH in lowlanders, possibly to adjust the hypoxic chemoreflex for life in high-altitude hypoxia.

The hypoxia tolerance of eight related African mole‐rat species rivals that of naked mole‐rats, despite divergent ventilatory and metabolic strategies in severe hypoxia

“…We measured the ventilatory and metabolic responses to acute hypoxia using plethysmography and respirometry techniques similar to those used previously for mole-rats and other small mammals. 22,[35][36][37] Mole-rats were individually placed, unrestrained, inside a 1 L (C.h.m., C.h.p., C.h.h., F.d., G.c. and H.e.)…”

Oxygen—to little, too much or just right

“…In the respiratory system, Ivy et al, in deer mice, observed high alveolar ventilation and oxygen uptake rates without changes in the carotid bodies, which in lowlanders adjust the hypoxic chemoreflex to high altitude hypoxia. Barna et al investigated the role of purinergic receptors in central breathing control, while a number of excellent studies have recently taken a closer look at pulmonary vascular wave dynamics, vasomotor function and vessel wall architecture and dynamics .…”

Different solutions to restoring oxygen delivery at altitude

“…In the present issue, Ivy et al . begin to explore the mechanisms underlying these evolved differences in the control of breathing.…”

“…The F1 progeny of each population were raised to adulthood under identical low altitude conditions and then were acclimated to normoxia or hypobaric hypoxia (12 kPa, simulating hypoxia at ~4300 m) for 5 months. Ivy et al . then recorded the effects of stepwise reductions in inspired O 2 on ventilation, respiratory water loss, heart rate, arterial O 2 saturation, metabolism and growth of the carotid body.…”

“…Ivy et al . speculate that the enhanced responses seen in the hypoxia‐acclimated, low‐altitude mice result from the growth of the carotid bodies and are associated with persistent sympathetic activation.…”