Heidenhain, Rudolf Peter Heinrich

Born Jan. 29, 1834, in Marienwerder; died Oct. 13, 1897, in Breslau. German physiologist and histologist. Professor at the University of Breslau (from 1859).

In 1856, Heidenhain discovered the influence of the intensity of direct current on the effect it produces by stimulating motor nerves. Analyzing the so-called tonomotor phenomenon—that is, the slow tonic contraction of tongue muscles that have a transected motor nerve after stimulation of the peripheral end of the sensory lingual nerve—Heidenhain showed that it is caused by the side effect of vasodilatation. He discovered that stimulating certain places in the cerebral cortex inhibits the skeletal musculature and that heat production in muscles is related to the conditions of their activity, including blood circulation, stress, and intensity of stimulation. He recorded the emission of heat during solitary muscle contraction.

Heidenhain found that renal epithelium plays an active part in urine production and that the corresponding cellular elements are involved in lymph formation and absorption from the intestines. The gastric glands, according to Heidenhain, are influenced by two kinds of nerves; secretory, which are responsible for secretion, and trophic, which determine the chemical transformations in the gland. Heidenhain showed that pepsin and hydrochloric acid are secreted by various glandular cells of the stomach. He proposed the method of the isolated stomach, whose shortcomings were revealed and corrected by I. P. Pavlov.