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Updated: Jul 23, 2026

Assessment of Pulmonary Capillary Blood Volume, Membrane Diffusing Capacity, and Intrapulmonary Arteriovenous Anastomoses During Exercise
Published on: February 20, 2017
Avian intrapulmonary chemoreceptor discharge rate is increased by anion exchange blocker 'DIDS'
1Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011-5640, USA.
Abstract:
Avian intrapulmonary chemoreceptors (IPC) are neurons that sense lung P(CO(2)) and provide phasic feedback for the control of breathing in birds. To try to understand mechanisms of CO(2) transduction and intracellular pH regulation in IPC, the anion exchange inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) was used to block transmembrane Cl(-)/HCO(3)(-) transport. Single-unit IPC discharge rates were measured at steady intrapulmonary CO(2) levels and during step changes in CO(2) in 15 anesthetized, unidirectionally ventilated adult mallard ducks (Anas platyrhynchos). Measurements were repeated after giving 50, 100 and 200 micromol/kg cumulative i.v. dosages of DIDS. Mean IPC discharge rates at steady (tonic) P(CO(2)) levels were significantly increased by 100 and 200 micromol/kg DIDS, but not by 50 micromol/kg DIDS. Mean dynamic (phasic) IPC responses to CO(2) steps were not significantly affected by DIDS. Results indicate that the DIDS-sensitive Cl(-)/HCO(3)(-) membrane exchanger is involved with tonic CO(2) signal transduction in IPC. However, because some individual IPC were unaffected by DIDS, yet still altered their discharge rate with CO(2), additional mechanisms besides the Cl(-)/HCO(3)(-) exchange are probably required for CO(2) chemotransduction in IPC.
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