Angiotensin II modulates respiratory and acid-base responses to prolonged hypoxia in conscious dogs

sin II modulates respiratory and acid-base responses to prolonged hypoxia in conscious dogs. Am. J. Physiol. 275 (Regulatory Integrative Comp. Physiol. 44): R390–R399, 1998.—We tested the hypothesis that angiotensin II (ANG II) contributes to ventilatory and acid-base adaptations during 3–4 h of hypoxia (partial pressure of O2 in arterial blood < 43 Torr) in the conscious dog. Three protocols were carried out over 3–4 h in five dogs: 1) air control, 2) 12 % O2 breathing, and 3) 12 % O2 breathing with ANG II receptors blocked by infusion of saralasin (0.5 µg·kg21 ·min21). After 2 h of hyp-oxia, expired ventilation and alveolar ventilation progres-sively increased, and the partial pressure of CO2 in arterial blood and the difference between the arterial concentrations of strong cations and strong anions ([SID]) decreased. When the hypoxic chemoreceptor drive to breathe was abolishe