Abstract
Studies were carried out on isolated chromaffin granules from bovine adrenal medullae. The granules were purified by Millipore filtration and incubated at 30°C. ATP caused a concentration-dependent release of catecholamines at concentrations from 0.0625 to 0.5 mM. AMP, cyclic 3',5'-AMP3, and CTP were ineffective, while ADP and adenosine tetraphosphate had some releasing activity. ATP-evoked release was observed in the presence of Mg or Mn, but not in that of Ca, Ba, or Sr. Na and K were equally effective in supporting release by ATP + Mg, but 0.3 M sucrose abolished the response. AMP and NEM also inhibited ATP-evoked release. There was a correlation between catecholamine release and ATPase activity. Discharge of catecholamines was accompanied by liberation of ATP and protein but not of cholesterol. A model is proposed to explain the present results in relation to catecholamine secretion in vivo.
ACKNOWLEDGMENTS We wish to acknowledge the support and encouragement of Dr. W. W. Douglas and the technical assistance of Mr. A. Hooper. Supported by U.S.P.H.S. grants 5TI-GM-65-09, 5K3-GM-25304, and 5RO1-NB-04006.
- Copyright ©, 1967, by Academic Press Inc.
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