Histidine-related compounds (HRC) were analyzed in fish skeletal muscle as a means of identifying their precise role in intracellular buffering. Fish muscle was used because it contains two functionally and spatially distinct fiber types, red and white. Two fish species, rainbow trout (Salmo gairdneri) and the Pacific blue marlin (Makaira nigricans), were studied because these species demonstrate widely different activity patterns. Marlin red and white muscle buffer capacity was two times higher than trout with white muscle, buffering being two times greater than red in both species. Buffer capacity was highest in the 6.5-7.5 pH range for all tissues, which corresponded to their high anserine levels. The titrated HRC buffering was greater than the observed HRC buffering, which suggested that not all HRC were available to absorb protons. The HRC contribution to total cellular buffering varied from a high of 62% for marlin white to a low of 7% for trout red. The other principal buffers were found to be phosphate and protein with taurine contributing within red muscle in the 7.0-8.0 pH range. HRC were found to be dominant in skeletal muscle buffering by principally accounting for the buffering capacity differences found between the species and fiber types.

Low-moderate steady-state exercise elicits a neuroautonomic cardiovascular dysfunction in concussed athletes that is not present in a rested state. This dysfunction alludes to an exercise induced uncoupling between the autonomic and cardiovascular systems.

Successful application of fish-revival techniques in commercial fishing prior to release of nontarget species requires clear evidence that recovery devices do indeed improve physiological status and minimize postcapture delayed mortality. This study provides such evidence for a newly designed recovery box (Fraser box) that assisted gill ventilation. Immediately after capture by gillnet, adult coho salmon (Oncorhynchus kisutch) were in a state of severe metabolic exhaustion and stress, based on a comprehensive analysis of plasma and muscle tissue. However, when placed in a Fraser recovery box for 1-2 h, both lethargic and vigorous fish showed significant metabolic recovery and their ability to swim was also quickly restored. An emphatic demonstration of the benefit of the Fraser box was the successful revival of >90% of fish that appeared dead at capture. Furthermore, postcapture delayed mortality was only 2.3% after a 24-h observation period. Therefore, in the context of commercial salmon gillnet fishing, revival of nontarget coho salmon in a Fraser box, in combination with a soak time (total time the gillnet is in the water) £ 70 min and careful fish handling to minimize physical trauma, could improve physiological status, restore swimming ability, and markedly reduce postcapture delayed mortality. Farrell et al.Résumé : Pour que l'application de techniques de réanimation de poissons non-ciblés avant leur rejet à l'eau lors de pêches commerciales soit un succès, il faut s'assurer que les moyens de rétablissement améliorent de fait la condition physiologique et minimisent la mortalité différée après la capture. Notre étude fournit une telle assurance dans le cas de l'utilisation d'une enceinte de rétablissement récemment conçue (la boîte de Fraser) qui favorise la ventilation des branchies. Immédiatement après leur capture au filet maillant, les Saumons coho adultes (Oncorhynchus kisutch) sont en état d'épuisement métabolique et de stress, comme l'indique une analyse détaillée du plasma et du tissu musculaire. Cependant, après 1-2 h dans la boîte de rétablissement de Fraser, tant les poissons léthargiques que les poissons vigoureux font preuve d'un rétablissement métabolique significatif et retrouvent rapidement leur capacité de nage. Une démonstration significative de l'efficacité de la boîte de Fraser est que plus de 90 % des poissons qui semblaient morts à la capture s'y sont rétablis avec succès. De plus, la mortalité différée après la capture était de seulement 2,3 % après une période d'observation de 24 h. Dans le cas de la pêche commerciale au saumon à l'aide de filets maillants, la réanimation des Saumons coho non ciblés par la pêche, combinée à un temps de mouillage des filets de £ 70 min et une manutention soignée des poissons de façon à minimiser les traumatismes physiques, peut donc améliorer la condition physiologique, rétablir la capacité de nage et réduire de façon marquée la mortalité différée.[Traduit par la Rédaction] 1946

The incretins, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) are responsible for >50% of nutrient-stimulated insulin secretion. After being released into the circulation, GIP and GLP-1 are rapidly inactivated by the circulating enzyme dipeptidyl peptidase IV (DP IV). The use of DP IV inhibitors to enhance these insulinotropic hormonal axes has proven effective on an acute scale in both animals and humans; however, the long-term effects of these compounds have yet to be determined. Therefore, we carried out the following study: two groups of fa/fa Zucker rats (n ‫؍‬ 6 each) were treated twice daily for 3 months with the DP IV inhibitor P32/98 (20 mg ⅐ kg ؊1 ⅐ day ؊1 , p.o.). Monthly oral glucose tolerance tests (OGTTs), performed after drug washout, revealed a progressive and sustained improvement in glucose tolerance in the treated animals. After 12 weeks of treatment, peak OGTT blood glucose values in the treated animals averaged 8.5 mmol/l less than in the controls (12.0 ؎ 0.7 vs. 20.5 ؎ 1.3 mmol/l, respectively). Concomitant insulin determinations showed an increased earlyphase insulin response in the treated group (43% increase). Furthermore, in response to an 8.8 mmol/l glucose perfusion, pancreata from controls showed no increase in insulin secretion, whereas pancreata from treated animals exhibited a 3.2-fold rise in insulin secretion, indicating enhanced ␤-cell glucose responsiveness. Also, both basal and insulin-stimulated glucose uptake were increased in soleus muscle strips from the treated group (by 20 and 50%, respectively), providing direct evidence for an improvement in peripheral insulin sensitivity. In summary, long-term DP IV inhibitor treatment was shown to cause sustained improvements in glucose tolerance, insulinemia, ␤-cell glucose responsiveness, and peripheral insulin sensitivity, novel effects that provide further support for the use of DP IV inhibitors in the treatment of diabetes. Diabetes 51: 943-950, 2002

Maximum O2 and CO2 fluxes during exercise were less perturbed by hypoxia in Quechua natives from the Andes than in lowlanders. In exploring how this was achieved, we found that, for a given work rate, Quechua highlanders at 4,200 m accumulated substantially less lactate than lowlanders at sea level normoxia (approximately 5-7 vs. 10-14 mM) despite hypobaric hypoxia. This phenomenon, known as the lactate paradox, was entirely refractory to normoxia-hypoxia transitions. In lowlanders, the lactate paradox is an acclimation; however, in Quechuas, the lactate paradox is an expression of metabolic organization that did not deacclimate, at least over the 6-wk period of our study. Thus it was concluded that this metabolic organization is a developmentally or genetically fixed characteristic selected because of the efficiency advantage of aerobic metabolism (high ATP yield per mol of substrate metabolized) compared with anaerobic glycolysis. Measurements of respiratory quotient indicated preferential use of carbohydrate as fuel for muscle work, which is also advantageous in hypoxia because it maximizes the yield of ATP per mol of O2 consumed. Finally, minimizing the cost of muscle work was also reflected in energetic efficiency as classically defined (power output per metabolic power input); this was evident at all work rates but was most pronounced at submaximal work rates (efficiency approximately 1.5 times higher than in lowlander athletes). Because plots of power output vs. metabolic power input did not extrapolate to the origin, it was concluded 1) that exercise in both groups sustained a significant ATP expenditure not convertible to mechanical work but 2) that this expenditure was downregulated in Andean natives by thus far unexplained mechanisms.