The role of the central thromboxane A2 in cardiovascular effects of a phospholipase A2 activator melittin administrated intracerebroventricularly in normotensive conscious rats.
The current study was designed to determine the cardiovascular effect of centrally administrated melittin, a phospholipase A2 (PLA2) activator, and the mediation of central thromboxane A2 (TXA2) and its receptors in normotensive conscious rats. Studies were performed in normotensive male Sprague Dawley rats injected intracerebroventricularly (i.c.v.) with melittin. Melittin (1.5, 3.0, 6.0 microg/5.0 microl; i.c.v.) caused dose- and time-dependent increases in mean arterial pressure (MAP) and decrease in heart rate (HR). Maximal effects were observed 5-10 min after 3.0 microg dose of melittin. In order to test the mediation of central TXA2 and its central receptors in the cardiovascular effect of melittin, the rats were pretreated with furegrelate (500.0 microg; i.c.v.), a TXA2 synthesis inhibitor, and SQ-29548 (8.0 microg; i.c.v.), a TXA2 receptor antagonist, 15 min prior to melittin (3.0 microg). Furegrelate or SQ-29548 partially inhibited the pressor effect and bradycardia elicited by melittin. In conclusion, our findings show that centrally administered melittin increases MAP and decreases HR in conscious rats. Moreover, according to our findings, central TXA2 and its receptors may in part mediate melittin-induced cardiovascular effects.
Yalcin
Murat
M
Department of Physiology, Faculty of Veterinary Medicine, Uludag University, Gorukle, 16059 Bursa, Turkey. muraty@uludag.edu.tr
Ak
Fusun
F
Erturk
Melih
M
D000818:Animals; D001572:Benzofurans / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D019086:Bridged Bicyclo Compounds, Heterocyclic; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005231:Fatty Acids, Unsaturated; D006339:Heart Rate / Q000187:drug effects*; D006834:Hydrazines / Q000494:pharmacology; D008297:Male; D008555:Melitten / Q000378:metabolism / Q000494:pharmacology*; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2; D051381:Rats; D017207:Rats, Sprague-Dawley; D044244:Receptors, Thromboxane A2, Prostaglandin H2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D013928:Thromboxane A2 / Q000378:metabolism*
D001572:Benzofurans; D019086:Bridged Bicyclo Compounds, Heterocyclic; D004791:Enzyme Inhibitors; D005231:Fatty Acids, Unsaturated; D006834:Hydrazines; D044244:Receptors, Thromboxane A2, Prostaglandin H2; D008555:Melitten; D013928:Thromboxane A2; C045749:SQ 29548; D010741:Phospholipases A; D054467:Phospholipases A2; C039936:furegrelate