Naslov
Effects of free fatty acids on insulin stimulated amino acid transport in cultured rat hepatocytes

Autori
Roša, Jagoda ; Roša, Josip

Izvornik
PERIODICUM BIOLOGORUM (0031-5362) 105 (2003), 2; 125-129

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
amino acid transport; insulin; insulin resistance; free fatty acids; oleic acid; protein kinase C

Sažetak
Aim. The aim of this study was to determine the possible role of free fatty acids in insulin signalling. Methods. Hepatocytes were isolated by a modified collagenase perfusion technique of Berry and Friend and cultured for 24 h in M199 serum-free medium. To assess amino acid transport hepatocytes were incubated in Hanks-Hepes medium containing ?-amino14C-isobutyric acid (AIB) to the final concentration of 1 mmol/L. One hour later the medium was removed and hepatocytes were quickly frozen in liquid nitrogen after three washes with cold saline. The cells were digested in 0.2 mol/L NaOH and a aliquot were taken for determination of protein and radioactivity. Results. In hepatocytes obtained from rats on standard diet insulin produced almost 100% increase of AIB transport (P<0.01). Free fatty acids did not change basal AIB transport but strongly reduced insulin effect (> 50%) (P<0.01). Reduction of insulin-stimulated transport was achieved one hour after addition of oleic acid. On the other side removing of oleic acid also very quickly after 3 hours restore normal condition. Pretreatment with phorbol 12- myristate 13-acetate significantly reduced (TPA) (P<0.01) insulin effect in normal cells. 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H 7) partially antagonises (P<0.01) the oleic acid induced reduction of AIB transport. Conclusion. Although classical paradigm defining the pathophysiology of insulin resistance have focused on the abnormal regulation, our data also support a role for fatty acids as an primary physiological modulator of insulin action. Reduction of insulin effect by oleic acid was probably result of changes in insulin receptor-kinase (IRK) activity involving of protein kinase C (PKC).

Izvorni jezik
Engleski

Znanstvena područja
Temeljne medicinske znanosti

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