Effect of Secretin Given into Portal or Peripheral Vein. ∗

Abstract

Intravenously injected secretin is considered generally to equal the physiological effect of the hormone as liberated during digestion. However, there is reason to assume a difference in effect on the pancreas between these 2 ways of entrance of the hormone into the circulation, because a number of hormones seem to be inactivated in the liver. The naturally secreted secretin most probably enters the portal circulation and passes through the liver first, while in intravenous injection it passes the liver only after it has been diluted in the general circulation (1). This concept is supported by results obtained with vivdialysis by Necheles and Lim (2). Previous workers, using rather crude preparations of secretin, found a weaker response of pancreatic secretion following its injection into the portal vein than into a systemic vein(3). However, Mellanby(1) using a more purified secretin, found no such difference. Our attention was focused on this question when we were able to obtain a highly purified secretin labelled with I¹³¹ †; following its intravenous injection, we found only low concentrations of I¹³¹ in the pancreas and high concentrations in the liver. We assumed this to indicate a primary concentration of secretin in the liver and possibly a secondary release into the circulation and to the pancreas. Furthermore, we believe that the highly purified secretin that is available now may yield more valid results than preparations made before 1926.

Methods. Adult male and female mongrel dogs were anesthetized with intravenous Nembutal; cystic duct, accessory pancreatic duct, and pylorus were ligated, a plastic tube was secured in the main pancreatic duct and connected to an electronic drop recorder.‡ Carotid blood pressure was recorded with a mercury manometer.