Effects of alternating blood flow restricted training and heavy-load resistance training on myofiber morphology and mechanical muscle function.

To investigate if short-term block-structured training consisting of alternating weeks of blood flow restricted low-load resistance training (BFR-RT) and conventional free-flow heavy-load resistance training (HL-RT) leads to superior gains in mechanical muscle function, myofiber size, and satellite cell (SC) content and myonuclear number compared with HL-RT alone. Eighteen active young participants (women/men: 5/13, 23 ± 1.2 yr) were randomized to 6 wk (22 sessions) of lower limb HL-RT [70-90% one repetition maximum (1-RM)] (HRT, n = 9) or block-structured training alternating weekly between BFR-RT (20% 1-RM) and HL-RT (BFR-HRT, n = 9). Maximal isometric knee extensor strength (MVC) and muscle biopsies (VL) were obtained pre- and posttraining to examine changes in muscle strength, myofiber cross-sectional area (CSA), myonuclear (MN) number, and SC content. MVC increased in both training groups (BFR-HRT: +12%, HRT: +7%; P < 0.05). Type II myofiber CSA increased similarly (+16%) in BFR-HRT and HRT (P < 0.05), while gains in type I CSA were observed following HRT only (+12%, P < 0.05). In addition, myonuclear number remained unchanged, whereas SC content increased in type II myofibers following HRT (+59%, P < 0.05). Short-term alternating BFR-RT and HL-RT did not produce superior gains in muscle strength or myofiber size compared with HL-RT alone. Noticeably, however, conventional HL-RT could be periodically replaced by low-load BFR-RT without compromising training-induced gains in maximal muscle strength and type II myofiber size, respectively.NEW & NOTEWORTHY The present data demonstrate that periodically substituting heavy-load resistance training (HL-RT) with low-load blood flow restricted resistance training (BFR-RT) leads to similar gains in type II myofiber CSA and muscle strength as achieved by HL-RT alone. Furthermore, we have for the first time evaluated myonuclear content and myonuclear domain size before and after training intervention across separate fiber size clusters and found no within-cluster changes for these parameters with training.

[The biotransformation of the anticonvulsant 4-p-chlorophenylpyrrol-3-morpholino-2-carboxylic acid methyl ester (AWD 140-076)]. / Untersuchungen zur Biotransformation des Antikonvulsivums 4-p-Chlorophenylpyrrol-3-morpholino-2-carbonsäuremethylester (AWD 140-076).

4-p-Chlorphenylpyrrole-3-morpholino-2-carboxylic acid methylester (1; AWD 140-076) is a substance with anticonvulsive properties. After p.o. administration in male wistar rats many metabolites in relatively small concentration are excreted in urine and faeces, six of them could be isolated and identified as quantitative dominating compounds. Compound 1 is attacked in different sites of the molecule by the cytochrome P-450 system. At the morphine ring N- and O-dealkylation reactions take place leading to the cleavage of the ring. After that a stepwise degradation by oxidative and reductive processes occurs. Further reactions concern the N-oxidation of the morpholine nitrogen as well as the hydroxylation of the pyrrole skeleton forming the main metabolites. 5 metabolites are also present as sulfate or glucuronide conjugates. The quantity ratio of the phase I to phase II metabolites amounts to 9:1. In the in vitro test system isolated perfused rat liver and rat hepatocytes culture solely the two main metabolites are formed. Compound 1 is characterized by enzyme inducing activities. The oxidative demethylation of p-nitroanisole is increased 4-fold after pretreatment.