The role of phospholipase C in arginine vasopressin secretion by rat hypothalami in vitro.
The role of phosphatidylcholine (PC) and phosphatidylinositol (PI) specific phospholipase C (PLC) enzymes in the release of immunoreactive arginine vasopressin (ir-AVP) from rat hypothalami in vitro was examined. PC-PLC (0.05-01 U ml-1) increased ir-AVP release but PI-PLC (0.01-0.5 U ml-1) did not. The response to a submaximal concentration of PC-PLC (0.075 U ml-1) was inhibited by the protei kinase C (PKC) inhibitor Ro 31-8220 (40 microM) and by removal of extracellular Ca2+ but was unaffected by the nitric oxide (NO) precursor L-arginine (1 mM), the NO synthase inhibitor N omega-nitro-L-arginine benzyl ester (1 mM) and the phospholipase A2 (PLA2) inhibitors quinacrine (100 microM) and dexamethasone (1 microM). The results suggest that PC-PLC plays an important role in AVP secretion. The responses to PC-PLC appear to be mediated by PKC but not by changes in NO synthase or PLA2 activity.
Wayte
J
J
Department of Pharmacology, Charing Cross and Westminster Medical School, London, UK.
Buckingham
J C
JC
Cowell
A M
AM
D000818:Animals; D001127:Arginine Vasopressin / Q000032:analysis / Q000378:metabolism*; D004075:Diglycerides / Q000096:biosynthesis*; D007031:Hypothalamus / Q000378:metabolism / Q000502:physiology*; D007150:Immunohistochemistry; D008297:Male; D009924:Organ Culture Techniques; D010713:Phosphatidylcholines / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D010738:Type C Phospholipases / Q000502:physiology*
D004075:Diglycerides; D010713:Phosphatidylcholines; D010716:Phosphatidylinositols; D001127:Arginine Vasopressin; D010738:Type C Phospholipases