A vagally mediated response to metabolic acidosis in anesthetized rabbits.
Pentobarbital sodium-anesthetized rabbits received 10-min infusions of acetic, lactic, or propionic acid delivered via a catheter to the right atrium at a rate of 1 mmol/min (n = 14). Arterial [H+] increased by 35.8 +/- 7.6 (SD) nmol/l, a decrease in pH of 0.27 +/- 0.04. By the end of the infusion period respiratory frequency (f), tidal volume (VT), and minute ventilation (V) had increased by 15.5 +/- 6.2 breaths/min, 7.3 +/- 2.7 ml, and 0.86 +/- 0.34 l/min, respectively. Arterial PCO2 (PaCO2) increased initially, but isocapnia was established during the latter half of the infusion (delta PaCO2 = 0.4 +/- 2.0 Torr). Bilateral cervical vagotomy eliminated the f response to acid infusions (n = 9, delta f = 0.6 +/- 2.4 breaths/min). The increase in VT (12.6 +/- 3.1 ml) was greater, but that in V (0.39 +/- 0.11 l/min) was less than in intact animals (P less than 0.05). PaCO2 remained elevated throughout the infusion (delta PaCO2 = 5.5 +/- 2.6 Torr), resulting in a greater rise in arterial [H+] (delta[H+]a = 53.6 +/- 6.6 nmol/l, delta pHa = -0.37 +/- 0.04). It is concluded that vagal afferents play a role in the f response to acute metabolic acidosis in rabbits.
Maskrey
M
M
Department of Thoracic Medicine, University of London, Midhurst, West Sussex, United Kingdom.
Trenchard
D
D
D000085:Acetates / Q000008:administration & dosage; D019342:Acetic Acid; D000138:Acidosis / Q000503:physiopathology*; D000140:Acidosis, Lactic / Q000503:physiopathology; D000818:Animals; D011422:Propionates / Q000008:administration & dosage; D011817:Rabbits; D012119:Respiration; D014628:Vagotomy; D014630:Vagus Nerve / Q000503:physiopathology*
D000085:Acetates; D011422:Propionates; C029658:propionic acid; D019342:Acetic Acid