Irreversible damage to rostral pontine nuclei in adult awake goats does not alter the ventilatory regulation of eupneic PaCO2 and the ventilatory response to hypercapnia

Abstract

Controversies regarding the role of rostral pontine nuclei (RPN) in the control of breathing have prompted us to chronically implant microtubules into the rostral pons of 6 goats to assess the regulation of eupneic PaCO2 and the ventilatory response to hypercapnia following irreversible damage to RPN. All goats recovered uneventfully and 3 weeks after implantation PaCO2 and CO2 sensitivity were within normal limits. Whole body CO2 sensitivity was assessed by increasing inspired CO2 to 3, 5, and 7% at 5‐minute intervals, subsequent to breathing room air for 30 minutes. CO2 sensitivity was expressed as ΔVI/ΔPaCO2. Arterial blood was sampled during the control and min 4 of each hypercapnic level. As shown in the Table, CO2 sensitivity and resting PaCO2 were unaffected following sequential RPN damage (microtubule implantation, microdialysis probe insertion, and intra‐cranial ibotenic acid injection, respectively). We conclude that damage to RPN does not alter regulation of eupneic PaCO2 and the ventilatory response to hypercapnia. CO2 sensitivity and resting PaCO2 are not significantly changed subsequent to RPN damage. Pre‐implant Post‐implant Post‐microdialysis Post‐ibotenic acid CO2 sensitivity (l/min/mmHg) 2.24 2.25 2.08 2.30 Resting PaCO2 (mmHg) 40.24 39.57 38.67 40.00 No significant difference between variables by one‐way ANOVA (P<0.05). Supported by the Department of Veterans Affairs and NIH HL25739.