Introduction
Secretin belongs to the vasoactive intestinal peptide/pituitary adenylate cyclase activating peptide family and is a basic polypeptide. It consists of amino acids and 27 amino acid residues, also known as gastrointestinal peptides. The secretin is a gastrointestinal regulating hormone, and the physiological dose of secretin relaxes the stomach and inhibits gastric activity. Secretin has a regulatory effect on human lower esophageal sphincter (LES) lasso fibers and hook fibers.
Pharmacologic action
The secretin receptor belongs to the G protein-coupled receptor family. Before and after the use of secretin, the cpm value of the lasso fibers and the hook fibers are increased and the percentages are not significantly different. Secretin activates cyclic adenosine monophosphate (cAMP) by activating adenylate cyclase (AC) coupled to G protein, which in turn activates protein kinase A (PKA), which inactivates RhoA leading to smooth muscle cell relaxation. AC agonist Forskolin potentiates secretin-relaxed lasso fibers and hook-like fibroblasts, and there was no significant difference between the two. cAMP inhibitors inhibit the secretin effect. In conclusion, activation of the G protein Gα coupled to the secretin receptor activates the secretion of lasso fibers and hook fibers by secretin, which activates AC to produce cAMP and activate PKA, resulting in smooth muscle relaxation.
Function
Secretin can relax the human LES lasso fiber and hook fiber cells in a concentration-dependent manner. The leptin-induced lasso fiber is different from the hook-shaped fiber in relaxation. The lasso fiber produces a more intense relaxation response, and the hook fiber has a weaker diastolic response. The effect of secretin on the diastolic activity of lasso fibers and hook fibers. The concentration of secretin is 10 -6 mol/L, which has the strongest relaxation effect on the lasso fiber and the hook fiber. cAMP inhibitors block the relaxation of secretin on lasso fibers and hook fibers, but there is no significant difference between the two.
Pharmacokinetics and metabolism
The dose of secretin that produces the greatest irritation to humans, dogs, and pigs is 1 intravenous unit per hour or hourly per kilogram of body weight, equivalent to 200 to 250 nanograms. The secretin has a half-life of 4.1 minutes and a metabolic clearance of 15 ml/min·kg body weight. The subcutaneous administration of secretin is half-lived for 100 minutes and intravenously for 10-90 minutes.
References:
1. Bayliss, W. M., & Starling, E. H. (1902). The mechanism of pancreatic secretion. The Journal of physiology, 28 (5), 325-353.
