STUDIES ON CONDITIONS OF ACTIVITY IN ENDOCRINE ORGANS

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Abstract
After a suitable dose of ergotoxine, adrenin produces a fall of blood pressure, whereas stimulation of the hepatic nerves evokes a prolonged rise. Stimulation of the lower abdominal sympathetic chains causes an initial fall of pressure, succeeded by a rise comparable to that obtained from hepatic nerve excitation. It is concluded that the substance liberated from the liver region and that liberated from the legs and tail are similar, i.e., sympathin, and that sympathin differs from adrenin. Both sympathin and adrenin accelerate the heart and cause, before ergotoxine, contraction of leg and spleen volumes. After ergotoxine, however, sympathin from the liver affects only minimally the leg volume, whereas adrenin evokes a marked expansion. The different action on blood pressure is thus apparently due to different effects on vasodilator systems. Confirmation: a small dose of adrenin induces contraction of the nictitating membrane and an increase of leg volume; an amount of sympathin from the liver haying even less effect on the membrane produces a striking decrease of leg volume. To test whether there might be inhibitory as well as excitatory effects from sympathin the denervated nictitating membrane was selected as a structure contracted, and the denervated non-pregnant uterus of the cat was selected as a structure inhibited by sympathetic nerve impulses. Now the splanchnic nerves, having contractile and inhibitory effects, cause, when stimulated, contraction of the membrane and relaxation of the uterus. The hepatic nerves, having only contractile effects, cause, when stimulated, contraction of the membrane, but they have no effects on the uterus. Stimulation of the cardiac sympathetic supply (having accelerators and coronary dilators) produces contraction of the membrane and slight relaxation of the uterus; the latter effect can be abolished by reducing the stimulus, whereas the membrane still responds. The inference is drawn that there are two kinds of sympathin: sympathin E, excitatory, released into the circulation when structures are excited by the sympathetic, and producing elsewhere exclusively excitatory sympathomimetic effects; and sympathin I, inhibitory, liberated from structures which are inhibited by the sympathetic, and causing exclusively inhibitory sympathomimetic responses in other organs than those directly stimulated.