Catecholamine-synthesizing enzymes in the rat adrenal gland during exposure to cold.

KVET&ANSK+, RICHARD, GEORGE P. EEWIRTZ, VIRGINIA K. WEISE, AND IRWIN J. KOPIN. CQtacholamine-synthesizing enzymes in the rat adrmal gland during exposuw to cold. Am. J, Physiol. 220(4) : 928-931. 1971 .-Rats were continuously exposed to a temperature of 3 C for 1, 7, 21, or 42 days. Adrenal epinephrine was decreased after I day but had returned to control levels at 7, 21, or 42 days. Adrenal norepinephrine was unchanged from controls after 1 day but increased after 7, 21, or 42 days. Levels of adrenal tyrosine hydroxylase were significantly increased after 7 or 21 days of exposure, but returned to control levels after 42 days. Dopamine-/3-hydroxylase levels were increased 1, 7, and 21 days after exposure; after 42 days the activity was less than that found after 21 days but higher than that in control animals. Adrenal phenylethanolamine-N-methyl transferase levels did not increase to the same extent as tyrosine hydroxylase or dopamine-p-hy.droxylase levels. Phenylethanolamine-N-methyl transferase was increased after 7 or 21 days of exposure but not after 42 days. The initial rise and subsequent return toward normal levels in adrenal enzyme levels follows previously reported patterns of urinary excretion of epinephrine and norepinephrine found during cold exposure and coincides with the reported development of increased sensitivity of the tissues to catecholamines.