Effects of Acetazolamide on the Time Course of the CO2 Response of Carotid Body in the Newborn Kitten

In adult cats, peripheral chemoreceptors respond to a step increase in PCO2 by a rise in activity to a maximum and then adapt to a lower steady level within one minute. It has been shown that the transient peak response is entirely dependent on the catalyzed CO2 hydration and disappears after carbonic anhydrase inhibition (Black et al., 1971). In newborn kittens, the dynamics of response of peripheral chemoreceptors are different from that observed in adult cats (Marchal et al., 1992). It is known that neither the chemosensory activity (Hanson, 1986) nor the carbonic anhydrase activity (Maren, 1967) is mature at birth. However, the dynamics of the hypercapnic response of the peripheral chemoreceptors in newborns remains unknown.