The effects of cold exposure and cold plus phenoxybenzamine treatment on tyrosine hydrox-ylase (TH) activity and TH m RNA levels were investigated in the adrenal medulla of Sprague Dawley (SD) rats. SD rats were exposed to cold (4 °C) for 48 hours. Phenoxybenzamine was injected intra-peritoneally (i.p) at 20 mg/kg, which was prepared in 5% ethanol containing 0.9 % NaCL TH activity was measured by monitoring the formation of 3 H 2 O as a product of L-(3 H)-tyrosine hydroxylation, the formation of L-(3 H)-dopa from L-(3 H)-tyrosine. Total adrenal RNA was isolated and blotted onto a nylon membrane and the immobilized RNA was then hybridized from TH cDNA probe. TH mRNA was assayed by densitometric scanning of the autoradiograms with a videodensitometer. TH activity and mRNA levels were found to be significantly increased in the adrenal medulla of SD rats exposed to cold for 48 hours and treated with cold plus phenoxybenzamine (P

The effects of cold exposure and cold plus phenoxybenzamine treatment on tyrosine hydrox-ylase (TH) activity and TH m RNA levels were investigated in the adrenal medulla of Sprague Dawley (SD) rats. SD rats were exposed to cold (4 °C) for 48 hours. Phenoxybenzamine was injected intra-peritoneally (i.p) at 20 mg/kg, which was prepared in 5% ethanol containing 0.9 % NaCL TH activity was measured by monitoring the formation of 3 H 2 O as a product of L-(3 H)-tyrosine hydroxylation, the formation of L-(3 H)-dopa from L-(3 H)-tyrosine. Total adrenal RNA was isolated and blotted onto a nylon membrane and the immobilized RNA was then hybridized from TH cDNA probe. TH mRNA was assayed by densitometric scanning of the autoradiograms with a videodensitometer. TH activity and mRNA levels were found to be significantly increased in the adrenal medulla of SD rats exposed to cold for 48 hours and treated with cold plus phenoxybenzamine (P