title: Suppression of inositol phosphate release by cardiac myocytes isolated from fish oil-fed pigs.
abstract: Fatty acid composition of cardiac myocytes and release of inositol phosphates in pigs fed a fish oil supplemented diet was examined. Two groups of female pigs were fed diets supplemented with either 50 g/kg diet beef tallow (as control) or 50 g/kg diet fish oil (MaxEPA) rich in n-3 fatty acids. After 6 weeks of supplementation, the pigs were anesthetized and hearts were removed. Cardiac myocytes were isolated, lipid extracted and separated into non-polar and polar lipids by thin-layer chromatography. Fatty acid composition of individual neutral and polar lipid classes were examined by gas chromatography. To study the effect of membrane phospholipid modification on the phospholipase C (PLC) mediated release of inositol phosphates, cardiac myocytes were labelled with 4 microCi/mL myo-[2-(3)H]inositol for 48 h. After stimulation with epinephrine and phenylephrine, the water soluble [3H]inositol products were extracted, separated from [3H]inositol and [3H]glycerophosphoinositol by chromatography on Dowex AG 1-X8 and quantitated by scintillation counting. Cardiac myocytes isolated from fish oil-fed pigs had higher levels of n-3 polyunsaturated fatty acid in the non-esterified fatty acid and phospholipid fraction. Similarly, these cardiac myocytes had increased level of n-3 fatty and decreased n-6 fatty acids in all the phospholipid fractions, PE, PC, P1 and PS (p < 0.05). After stimulation, the levels of [3H]inositol trisphosphate (IP3) and [3H]inositol tetrakisphosphate (IP4) in cardiac myocytes isolated from fish oil-fed pigs were significantly reduced (p < 0.05) compared to myocytes isolated from beef tallow fed-pigs. This study for the first time has utilised adult cardiac myocytes to demonstrate the effect of n-3 PUFA supplementation on cardiac myocyte phospholipid fatty acid composition and release of second messengers.
authors.affiliation: Discipline of Nutrition and Dietetics, Faculty of Medicine and Health Sciences, University of Newcastle, Callaghan, NSW, Australia.
authors.forename: S S
authors.initials: SS
authors.lastname: Nair
authors.forename: J
authors.initials: J
authors.lastname: Leitch
authors.forename: M L
authors.initials: ML
authors.lastname: Garg
mesh_terms: D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D001145:Arrhythmias, Cardiac; D002470:Cell Survival; D002478:Cells, Cultured; D002845:Chromatography; D002849:Chromatography, Gas; D002855:Chromatography, Thin Layer; D019587:Dietary Supplements; D004837:Epinephrine / Q000494:pharmacology; D005227:Fatty Acids / Q000378:metabolism; D015525:Fatty Acids, Omega-3; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D005260:Female; D005395:Fish Oils / Q000494:pharmacology*; D007295:Inositol Phosphates / Q000096:biosynthesis* / Q000378:metabolism; D008055:Lipids / Q000032:analysis; D009206:Myocardium / Q000166:cytology*; D010656:Phenylephrine / Q000494:pharmacology; D010743:Phospholipids / Q000378:metabolism; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D012588:Scintillation Counting; D013552:Swine; D014280:Triglycerides / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D015525:Fatty Acids, Omega-3; D005231:Fatty Acids, Unsaturated; D005395:Fish Oils; D007295:Inositol Phosphates; D008055:Lipids; D010743:Phospholipids; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D014280:Triglycerides; C077446:Pikasol; C014575:glycerylphosphoinositol; D010656:Phenylephrine; D016718:Arachidonic Acid; D010738:Type C Phospholipases; D004837:Epinephrine