Oral theophylline changes renal carnitine palmitoyltransferase activity in rats

Background. Carnitine plays a critical role in lipid metabolism. Carnitine deficiency may adversely affect the oxidation of fatty acids and further aggravate abnormal lipid metabolism. Our objective was to investigate the effect of theophylline on the activity of carnitine palmitoyltransferase (CPT) in renal tissues of rats for 5-week-interval treatments. Methods. The study was a randomized, controlled animal study. Theophylline was given at 100 mg/kg body weight (b.w.)/day and effects were monitored after a treatment period of between 1 and 5 weeks. Results. Theophylline treatment caused a significant increase in renal CPT activity as compared to either control or placebo groups. Moreover, the results showed positive correlations between the renal concentration of long-chain acylcarnitine (LC), activity of CPT, urinary excretion of acylcarnitine (AC), and plasma concentration of LC (p <0.01), respectively. Conclusions. The observed changes in activity of renal CPT might be due to the result from theophylline-enhanced mobilization of lipid from adipose tissues that consequently stimulated an increased carnitine transport into the renal tissues to form palmitoylcarnitine groups for subsequent beta -oxidation inside the mitochondria. Thus, these accumulations of palmitoylcarnitine groups in mitochondria may increase the catalytic action of CPT. (C) 2001 IMSS. Published by Elsevier Science Inc.