The effect of glucagon and prostaglandin E₁ on cyclic AMP levels in liver of heat exposed hamsters

Cyclic AMP levels in liver slices of hamsters exposed to 35°C for 21 days and controls maintained at 22°C was found to be similar in basal conditions. Glucagon (10 μg/ml) caused 3.5 times elevation of cyclic AMP levels in control hamsters and 9 times elevation in 35°C exposed hamsters, thus a difference of 150% of the nucleotide concentration was found between the two experimental groups. When 10^-2M theophylline was added, the cyclic AMP levels were 80% higher in 35°C exposed hamsters both in the presence and absence of 10 μg/ml glucagon. The difference between controls and heat exposed animals was found to be the same when various concentrations of both glucagon or prostaglandin E1 were added to the liver slices. Adenylate cyclase activity was similar in both experimental groups, while low Km phosphodiesterase was significantly less active in the liver of 35°C exposed animals when compared to the controls.