The works of professor N.P. Kravkov in the area of endocrinology

This article describes the academic works of the N.P. Kravkov (1865–1924), a prominent Russian pharmacologist, on the study of the endocrine glands.

In N.P. Kravkov’s laboratory, via experiments on rabbits and dogs, a method of isolating the pancreas and extracting its perfusate was developed based on passing Ringer-Locke’s solution through the vessels of the isolated gland. It was discovered that the perfusate contains a substance that reduces the level of glucose in the blood of healthy animals and, in large doses, causes hypoglycaemic coma. N.P. Kravkov called this substance pancreotoxin.

The experiments of N.P. Kravkov’s followers on the isolated hearts of animals showed that, for a heart in the normal condition, pancreotoxin decelerates the heartbeat and reduces the amplitude of contractions, whereas for the heart tired above a certain threshold, the opposite effect is observed.

The study of the blood vessels in isolated ears of rabbits and the eyes of frogs revealed antagonism between pancreotoxin and adrenalin: pancreotoxin weakens the vasoconstrictive effect of adrenalin and reduces its influence on the size of the pupil in frogs. It was also shown that passing the perfusate containing pancreotoxin through the adrenal gland increases the secretion of adrenalin.

Later, pancreotoxin was obtained in the dried form and used to prepare a drug prescribed to patients with diabetes in hospitals.

From its properties, pancreotoxin turned out to be insulin. It should be noted that the news that insulin had been isolated from the pancreas by the Canadian researchers F. Banting and C. Best reached Russia only after the researchers in N.P. Kravkov’s laboratory had extracted and studied pancreotoxin from isolated pancreases. Thus, N.P. Kravkov and foreign researchers discovered this hormone independently.

In experiments on the isolated adrenal glands of cattle, N.P. Kravkov and his collaborators obtained the perfusate containing an adrenalin-like substance produced in the medulla of the adrenal gland and a muscarine-like substance produced by the suprarenal cortex.

The research by N.P. Kravkov and his followers on the physiology, pathology and pharmacology of the glands of internal secretion at the beginning of the 20th century has proved to be of great importance for the development of endocrinology in Russia.

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