Hiroshi Kouyama

Polyphosphate anions increase the activity of bovine spleen cathepsin D.

Abstract Bovine spleen cathepsin D is activated by polyphosphate anions when bovine serum albumin is used as substrate at pH 4.6. In the presence of ATP at 10 mM, the catheptic activity at this pH is enhanced as high as 17 times over the control. Similar activating effects were observed, though to varying degrees, with sodium tripolyphosphate, nucleotides, nucleotide analogues, CoA, polyU and yeast RNA. The possible mechanism and biological significance of the activation were discussed with regard to the intralysosomal polyanionic substance.

β-adrenergic stimulation of the adenosine 3′,5′- monophosphate system regulated by cholinergc stimuli in the prostate

Abstract Acetylcholine significantly inhibited isoproterenol-stimulated adenosine 3′,5′-monophosphate (cAMP) levels of rat prostatic tissue in a oncentration-dependent fashion. Atrropine but no hexamethonium reversed the inhibitory action of acetylcholine. Tetracaine and verapamil abolished the inhibitory effect of acetylcholine on isoproterenol-stimulated accumulationof cAMP. Exclusion of calcium also eliminated the effect of acetylcholine. Inhibitory regulation of cAMP levels was reproduced by the divalent cation ionophore A23187. These observation suggest that β-adrenergic stimulation of the cAMP system of the prostate is regulated by cholinergic stimulation involving a specific muscarinic receptor with calcium-dependent mechanism sensitive to verapamil or tetracine.

Studies on cyclic nucleotides in the adrenal gland : VI adenyl and guanyl cyclase in the adrenal medulla

Abstract Involvement of the adenyl and guanyl cyclase in the process of catecholamine-release evoked by acetylcholine has been studied in bovine adrenal medulla slices. Stimulation of catecholamine-release by acetylcholine was followed by a late increase in cyclic AMP levels at the time when the secretory stimulation was no longer observed. These results suggest that the delayed activation of the medullary adenyl cyclase is not involved in the secretory process but in the restoration or the synthesis of catecholamine after its release. No changes were demonstrated in cyclic GMP levels during incubation.