Central vs. peripheral chemoreceptors in ventilatory stimulation by Hacetate.
Intravenous infusion of Hacetate in conscious rabbits induces a greater decrease in cerebrospinal fluid (CSF) [HCO3-] and arterial CO2 partial pressure (PaCO2) than does HCl, HNO3, or Hacetate. To test whether acetate per se can stimulate central chemoreceptors, HCl- or Hacetate-acidified mock CSF was infused via the cisterna magna in conscious rabbits with catheters preimplanted under anesthesia. HCl infusion induced a greater decrease in PaCO2 refuting this hypothesis. To evaluate the role of the carotid body HCl and Hacetate were infused intravenously in an intact (CB+) and a chemodenervated group (CB-). In CB+ rabbits Hacetate infusion produced a greater decrease in PaCO2. In CB- rabbits, the fractional decrease in arterial PaCO2 was less for both acids compared with that of the CB+ rabbits, but it was significantly greater for Hacetate infusion (21.2 +/- 2.5%, mean +/- SE) than for HCl infusion (14.5 +/- 1.8%). Thus the carotid body is not necessary for the greater Hacetate ventilatory stimulation. The working hypothesis is that nonionic diffusion of Hacetate into brain or acetate replacement of HCO3- in CSF production lowers [HCO3-] near central chemoreceptors.
D000085:Acetates / Q000494:pharmacology*; D019342:Acetic Acid; D000136:Acid-Base Equilibrium; D000818:Animals; D001639:Bicarbonates / Q000134:cerebrospinal fluid; D001784:Blood Gas Analysis; D001921:Brain / Q000378:metabolism; D002245:Carbon Dioxide / Q000097:blood; D002628:Chemoreceptor Cells / Q000187:drug effects / Q000502:physiology*; D003714:Denervation; D011817:Rabbits
D000085:Acetates; D001639:Bicarbonates; D002245:Carbon Dioxide; D019342:Acetic Acid