摘要:

COSTILL, D.L., A. BARNETT, R. SHARP, W.J. FINK, and A. KATZ. Leg muscle pH following sprint running.Med. Sci. Sports Exerc., Vol. 15, No. 4, pp. 325–329, 1983. In an effort to compare the disturbances in leg muscle pH during sprint running, muscle biopsies were obtained from the gastrocnemius and vastus lateralis muscles of six healthy men (three endurance-trained and three nonendurance-trained) before and after a treadmill sprint run (TSR) to fatigue (54–105 s) at roughly 125% of their aerobic capacities. Following the TSR, repeated blood samples were taken from a hand vein and later analyzed for pH, Pco2, and lactic acid (HLa). The muscle specimens were analyzed in duplicate for pH and HLa. Resting-muscle pH was 7.03 ± 0.02 (&OV0312; ± SE) and 7.04 ± 0.01 for the gastrocnemius and vastus lateralis muscles, respectively. At the termination of the TSR, the pH in these muscles was 6.88 ± 0.05 and 6.86 ± 0.03, respectively. After a 400-m timed run on the track, the pH in the gastrocnemius of four of the subjects averaged 6.63 ± 0.03, while blood pH and HLa were 7.10 ± 0.03 and 12.3 mM, respectively. Although no differences in pH and HLa were observed between the vastus lateralis and gastrocnemius muscles at the end of the treadmill trial, it is speculated that the lesser disturbance in acid-base balance seen in endurance performers may have been due to a lesser production of metabolites in their running musculature when compared to nonendurance performers.

ISSN:0195-9131    

出版商:OVID    

年代:1983

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

PALMER, WARREN K. Hormonal regulation of myocardial lipolysis.Med. Sci. Sports Exerc., Vol. 15, No. 4, pp. 331–335, 1983. Although it has been documented that hormones promote lipolysis in the heart, an enzyme mediating this event has not been identified. We have found that perfusion of the rat heart with epinephrine, 3-isobutyl-l-methylxanthine, ordibutyryl (Bt2) cyclic AMP produced a biphasic effect on the activity of an enzyme having the properties of the intracellular fraction of lipoprotein lipase, i.e., stability in acetone:ether, pH optimum of 8.1, serum requirement, and sensitivity to heparin, NaCl, and protamine sulfate. We have termed this enzyme type L hormone-sensitive lipase (HSL). Perfusion with high concentrations of agent stimulate type L HSL activity, while perfusion with relatively low concentrations of agent inhibit enzyme activity. This inhibition is not observed if enzyme is extracted in organic solvent. The activity of type L HSL has a high negative (r>-0.93) relationship with the amount of triglyceride in the heart. Early attempts to purify this enzyme from control and epinephrine-stimulated hearts suggest that the enzyme can be obtained in two forms (control and activated). Although the data suggest that the mechanism of control of this enzyme is complex, it seems that the activity is controlled, in part, through cyclic AMP and protein kinase.

ISSN:0195-9131    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

OSCAI, LAWRENCE B. Type L hormone-sensitive lipase hydrolyzes endogenous triacylglycerols in muscle in exercised rats.Med. Sci. Sports Exerc., Vol. 15, No. 4, pp. 336–339, 1983. Lipoprotein lipase (LPL) exists in two distinct fractions in heart and skeletal muscle: LPL in capillary beds regulates the metabolism of chylomicrons and very low-density lipoproteins on the surface of the endothelial cells; in contrast, the intracellular fraction of LPL regulates endogenous triacylglycerol (TG) stores. The name of the intracellular enzyme has been changed from LPL to type L hormone-sensitive lipase (HSL) because it is responsive to epinephrine and glucagon levels in heart. In this symposium evidence will show that epinephrine also activates type L HSL in skeletal muscle. Further justification for the name change is that plasma lipoproteins do not exist in parenchymal cells of muscle and the intracellular enzyme possesses many of the classical characteristics described for LPL. Exercise activates type L HSL in heart and skeletal muscle with a concomitant decrease in muscle TG stores. These results provide evidence that under a normal physiological condition, such as exercise, type L HSL participates in the regulation of intramuscular TG stores.

ISSN:0195-9131    

出版商:OVID    

年代:1983

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:1983

数据来源: OVID