The effects of forced and voluntary diving on plasma catecholamines and erythrocyte pH in the aquatic anuran, Xenopus laevis.
The lactacidosis and hypoxaemia associated with enforced diving in Xenopus leads to a marked increase in circulating catecholamines, a phenomenon not observed during periods of voluntary diving. The magnitude of the catecholamine surge (predominantly noradrenaline) during an enforced dive appears to be matched to the severity of the hypoxaemia and/or acid-base disturbance. Indeed, a strong linear correlation was found between the decrease in arterial pH and the rise in plasma catecholamines that resulted from an enforced 60 min dive. During that time, the levels of plasma adrenaline and noradrenaline showed a strong inverse exponential correlation with arterial oxygen tensions (PaO2). Simultaneous measurements of red cell pH showed that Xenopus does not regulate its erythrocyte pH in the face of a plasma acidosis, unlike the adrenergically mediated pH regulation of red cells of certain teleost fish.
Boutilier
R G
RG
Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada.
Lantz
C J
CJ
D000693:Anaerobiosis; D000818:Animals; D002395:Catecholamines / Q000097:blood*; D004242:Diving; D004837:Epinephrine / Q000097:blood; D006863:Hydrogen-Ion Concentration; D009638:Norepinephrine / Q000097:blood; D010100:Oxygen / Q000097:blood; D014982:Xenopus laevis / Q000378:metabolism*
D002395:Catecholamines; D010100:Oxygen; D009638:Norepinephrine; D004837:Epinephrine