Motoo Oka

Effects of cyclic adenosine 3',5'-monophosphate and its dibutyryl derivatives on catecholamine synthesis in bovine adrenal medullary slices.

Recent results have suggested the possible role of cyclic adenosine 3’,5’-monophosphate (cyclic AMP) in control of catecholamine biosynthesis. Kvetnansky et al. found that administration of dibutyryl adenosine 3’,5’-monophosphate (DB-cyclic AMP) restored the adrenal activities of tyrosine hydroxylase and dopamine/3-hydroxylase in hypophysectomized rats [ I]. Waymire et al. observed that culture of mouse neuroblastoma tissue with DB-cyclic AMP for 1 and 3 days increased the tyrosine hydroxylase activity [2 1. Keen and McLean also reported that incubation of isolated rat superior cervical ganglia with DB-cyclic AMP increased the levels of dopamine

Catecholamine releasing factor in bovine adrenal medulla

-hydroxylase and noradrenaline (NA) [3]. Furthermore, Guidotti and Costa found that following administration of reserpine, aminophylline or carbamylcholine, the concentration of cyclic AMP in the adrenal medulla of rats increased several-fold [4]. They suggested that this might cause increase in tyrosine hydroxylase activity in the medulla [4,5]. This paper reports studies on the effects of cyclic AMP and DA-cyclic AMP on the synthesis of [14 Clcatecholamine (CA) from [I4 C] tyrosine in bovine adrenal medullary slices. Results showed that these cyclic nucleotides seem to increase [’ 4 C] CA synthesis mainly through their effects on the rate-limiting step catalyzed by tyrosine hydroxylase.

EFFECT OF ADENOSINE TRIPHOSPHATE AND MAGNESIUM ON THE RELEASE OF CATECHOLAMINES FROM ADRENAL MEDULLARY GRANULES.

Recently, the importance of cytoplasmic proteins in the process of catecholamine secretion has been pointed out. These proteins include microtubule protein (tubulin) [ 11, microfilament [2]> cyclic AMPdependent protein kinase [3] and contractile-like protein [4]. To obtain direct biochemical evidence of exocytosis in catecholamine release from the adrenal medulla, we studied the cytoplasmic proteins of chromaffine cells, finding a protein factor which stimulated catecholamine release from isolated granules containing catecholamine. Results indicated that the stimulatory effect of this protein factor was dependent on the presence of adenine nucleotides such as ATP, ADP and AMP. This factor required magnesium and a low concentration of calcium for its action.