ABSTRACT
Stimulation of secretion is accompanied by changes in energy metabolism of the secretory cells. Alterations in the concentration of adenosine triphosphate (ATP) or other nucleotides in the compartment may be concealed by the content of organelles. Additional compartmentation of the cytoplasm is caused by tight binding of nucleotides to proteins. During insulin release evoked by L-leucine and related compounds or by glucose of the extra amount of high energy phosphates produced in isolated islets originate from mitochondrial energy metabolism. In human platelets, which lack the creatine-phosphate system, eighty glycolysis is the main rapidly available source for ATP production. However, in the presence of exogenous glucose rapid stimulation of glucose metabolism in mast cells prevents decrease of the extragranular ATP level during the secretory responses. Stimulation of cholinergic receptors in the adrenal medulla triggers catecholamine release which is inhibited by blockade of the energy metabolism in the chromaffin cells.
