Pharmacological action of ANF are as follows::
1.it causes increase in sodium excretion this is mediated through the increase in glomerular filtration rate and decrease in proximal tubular sodium reabsorption
2. it inhibits secretion of renin aldosterone and vasopressin
3. ANF also decreases arterial blood pressure resulting from vasodilatation increase in cGMP levels and decrease in cytosolic free calcium concentration
4. ANF antogonizes the vasoconstrictor action of angiotension II
VASOACTIVE INTESTINAL PEPTIDE (VIP) AND SUBSTANCE-P
VIP is a 28-aminoacid peptide closely related structurally to secretin and glucagon it is widely distributed in central and peripheral nervous system it produces marked vasodilatation in most vascular beds including splanchinic pulmonary coronary renal and cerebral vessels Thus it causes fall in artrial blood pressure and increase in cardiac output VIP also relaxes tracheo bronchial and gastro intestinal muslces it stimulates intestinal water and electrolyte secretion promotes hepatic glycogenolysis causes neuronal excitatation and stimulates secretion of several hormones like growth hormone prolactin renin etc
substance -P is a decapeptide present in the central nervous system where it is thought to function as a neurotransmitter and in gastrointestinal tract where it plays a role as a local hormone
Substance -p is a potent vasodilator and produces hypotension it however stimulates contraction of venous intestinal and bronchial smooth muscle it also causes secretion in salivary gland and diuresis and natriuresis in kidney
0 Comments