Abstract
This work confirms the presence in the stria vascularis of guinea pigs of an adenylate cyclase (AC) system and describes several biochemical characteristics of this enzyme. the inner ears of guinea pigs were dissected in the cold after decapitation. the AC activity was evaluated by measurement of the transformation of [aL32P]ATP into [aL-32P]cAMP. Basal activity was 1544+ 441 (S.E.M.). N = 9. pmoles cAMP, 30 min−1. protein mg−. Stimulation by NaF demonstrated an activity of 58341827, N=9. pmoles cAMP. 30 min protein mg. Up to 25 min the formation of cAMP rose linearly with time. It was proportional to the protein concentration. the activity did not vary significantly in a pH range of 6.5-8.5. the influence of the concentration of ATP and of Mg++. respectively, in the incubation medium was studied. Preliminary assays of several hormones and pharmacological agents have not shown any alteration except with ethacrynic acid and furosemide. as reported by Thalmann.
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