Requirement for adenosine triphosphate for stimulation in vivo of ox growth-hormone release

Rotenone, carbonyl cyanide chloromethoxyphenylhydrazone and 2,4-dinitrophenol cause parallel falls in ox pituitary ATP content and growth-hormone release in the presence of 65mm-K⁺. Carbonyl cyanide chloromethoxyphenylhydrazone (0.4μg/ml) prevented the rise in growth-hormone release, but not the rise in 3′:5′-cyclic AMP content after addition of prostaglandin E₂ (1μg/ml). The rate of hormone release from unstimulated slices and from slices in the presence of Ba²⁺ at 2.3 or 6.9mm was proportional to the ATP content of the slices. Carbonyl cyanide chloromethoxyphenylhydrazone at concentrations that inhibited release in the presence of the three secretagogues did not alter the pituitary contents of Na⁺, K⁺ or Ca²⁺. The implications of these observations are discussed in terms of the mechanism of stimulus–secretion coupling.