Blood-gas,acid-base and catecholamine responses to lactic acid infusion in larval and adult Ambystoma tigrinum |
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Authors: | D F Stiffler S Eskandari |
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Institution: | (1) Biological Sciences Department, California State Polytechnic University, 91768 Pomona, CA, USA |
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Abstract: | Larval and adult Ambystoma tigrinum were subjected to acidosis by infusing lactic acid (2 M·g-1) into the peritoneal cavity. Blood was sampled at intervals to establish the time-course of the ensuing acidosis. Both larvae and adults became significantly acidotic after 1 h. The larval acidosis was more pronounced (-4 pH units versus-2 pH units) than adults due to greater extracellular buffering capacity (higher HCO3
-]) in adults. Both forms recovered in about 8 h. Larvae showed a typical increase in circulating norepinephrine during the initial stages of the acidosis; adults did not, having significantly lower norepinephrine titer than larvae during the acidosis. Both larvae and adults showed transient increases in PO2 during the acidosis. The 1 and 2 antagonists, timolol and butoxamine respectively, (0.2 g·g-1) were administered to separate groups of larvae. Butoxamine (2) delayed the recovery from the acidosis by prolonging the increase in arterial PCO2 and reversing the recovery of HCO3
-]. Timolol (1) did not delay recovery. We conclude that 2 receptors are involved in the catecholamine responses to acidosis in larvae. Catecholamines appear not to play the same role in adult acid-base disturbances as they seem to in larvae.Abbreviations RBC
red blood cell |
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Keywords: | pH-value Norepinephrine 1" target="_blank">gif" alt="beta" align="MIDDLE" BORDER="0">1 2" target="_blank">gif" alt="beta" align="MIDDLE" BORDER="0">2 Amphibia Ambystoma |
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