SEVERAL ANESTHETICS, BUT NOT DIETHYL-ETHER, CAUSE MARKED ELEVATION OFSERUM PARATHYROID-HORMONE CONCENTRATION IN RATS

The effects of anesthetics on serum parathyroid hormone (PTH) concentr ations were determined by a new homologous two-site immunoradiometric assay for rat PTH, Serum PTH concentrations (mean +/- SE) from ether-a nesthetized rats (14.7 +/- 1.5 pg/ml, n = 22) were not significantly d ifferent from those of decapitated unanesthetized female rats (113.0 /- 1.8 pg/mI, n = 21), Serum PTH concentrations in pg/ml (n = 4-14) fo r other anesthetics tested were: ketamine, 12.5 +/- 1.1; Na pentobarbi tal, 233 +/- 2.4; methoxyflurane (inhalation), 42.2 +/- 6.8; and xylaz ine combined with ketamine, 51.4 +/- 11.3 pg/ml. The latter two concen trations were significantly (p < 0.001) higher than the values for all other anesthetics and decapitation. Elevation of serum PTH induced by pentobarbital or ketamine + xylazine increased with time under anesth esia, Neither serum Ca2+ concentrations nor pH differed among any of t he groups, We conclude that anesthesia induced by pentobarbital, metho xyflurane, or ketamine + xylazine in rats leads to a marked elevation of serum PTH levels that appears to be related to the duration of anes thesia and not due to any measurable fall in serum Ca2+.