DIFFERENTIAL SENSITIZATION OF ADRENERGIC NEURO-EFFECTOR SYSTEMS BY THYROID HORMONE

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Abstract
[longdash]The effect of continuous intrayen. injs. of adrenalin on heart rate and on intestinal motility was detd. in un-anesthetized dogs before and during thyrotoxicosis produced by feeding powdered thyroid. The S-A node, which has an excitatory adrenergic innervation, showed hyper- sensitivity to adrenalin as indicated by a markedly increased accelerator response to a given inj. rate. The intestinal smooth muscle, which has an inhibitory adrenergic innervation, did not show hypersensitivity to adrenalin or to adrenergic neurohormones. The results indicate that differential sensitization of adrenergic neuro-effector systems constitutes a part of the thyrotoxic syndrome in the dog.