Characterization of the relationship between inspiratory neural discharges and the micturition reflex in decerebrate and urethane‐anesthetized adult in vivo rat

Abstract

Previous studies have characterized respiratory neural outputs during the micturition reflex (MR). However, these studies primarily were conducted in cats, and it is not known if the relationship seen in the cat model is maintained in rodent models. To begin to address this issue, we recorded bladder pressure and phrenic (Phr), hypoglossal (XII) and pudendal motor nerve activity in decerebrate or urethane‐anesthetized vagi‐intact adult rats during passive bladder filling and active bladder contraction. Spontaneous MRs were elicited by slow infusion of saline into the bladder. The data show increased Phr post‐inspiratory activity and a transient increase followed by a transient decrease in burst frequency (due to changes in TE). Small XII neural discharges were observed during expiration while the bladder actively contracted. In contrast to cat data, no changes in Phr or XII amplitude were observed. Finally, while severe hypercapnia and hypocapnia affected respiratory patterns, they did not affect the MR. We conclude that, while there are some similarities to the cat model, a different relationship between respiration and micturition occurs in rat. Supported by HL63175