Glucose administration before exercise modulates catecholaminergic responses in glycogen-depleted subjects

Gozal, David, Patrice Thiriet, Jean Marie Cottet-Emard,Dieudonné Wouassi, Emmanuel Bitanga, André Geyssant, JeanMarc Pequignot, and Marcel Sagnol. Glucose administration before exercise modulates catecholaminergic responses in glycogen-depleted subjects. J. Appl. Physiol. 82(1):248-256, 1997.In glycogen-depleted subjects (GD) a nonlinearincrease in epinephrine (Epi) and norepinephrine (NE) parallels bloodlactate (La) during graded exercise. The effect of glucose(Glc) supplementation and route of administration on theserelationships was studied in 26 GD athletes who were randomly assignedto receive 1.3 g/kg Glc by slow intravenous infusion (IV;n = 9), oral administration (PO;n = 9), or artificially sweetenedplacebo in 1 liter of water (Asp; n = 8) in the 2 h preceding a graded maximal exercise. Performance and Lawere similar among the three groups in normal glycogen (NG) or GDconditions. However, slightly improved performances were observed in GDcompared with NG and were associated with a shift to the right in Lacurves. Blood Glc concentrations were higher in IV and PO beforeexercise, but they rapidly decreased to lowest levels in IV, graduallydecreased over time in PO, and remained stable in Asp or NG. Insulinconcentrations were highest in IV and lowest in Asp and NG at onset ofexercise, rapidly decreasing in IV and PO although remaining at higherlevels than in Asp or NG. In contrast, higher serum levels of freefatty acids were measured during exercise in Asp with no significant differences in glucagon or glycerol among the three groups. Free andsulfated NE increases were smaller in IV than in PO and Asp onexhaustion. In contrast, free and conjugated Epi were most increased inIV, with smallest increases in Asp. Dopamine levels were most increasedin IV at exhaustion. We conclude that the changes of Epi and NEconcentrations, associated with the activation of glucoregulatorymechanisms, including hyperinsulinemia, display different magnitude andtime courses during exercise in GD subjects who receive oral vs.intravenous load of Glc before exercise. We speculate that themagnitude of insulin surge after acutely increased Glc before exercisein GD subjects may exert dissociative effects on adrenal-dependentglycogenolysis and on sympathetic responses.

     

Fluid regulatory hormone response to exercise after coca-induced body fluid shifts

Favier, R., E. Caceres, B. Sempore, J. M. Cottet-Emard, G. Gauquelin, C. Gharib, and H. Spielvogel. Fluidregulatory hormone response to exercise after coca-induced body fluidshifts. J. Appl. Physiol. 83(2):376-382, 1997.To determine the effect of coca chewing on heartrate (HR), mean arterial blood pressure (MAP), and plasma volume andtheir relationship with the hormones regulating cardiovascular and bodyfluid homeostasis, 16 male volunteers were examined at rest and during1 h of cycle exercise at ~75% of their peak oxygen uptake in twotrials separated by 1 mo. One trial was performed after the subjectschewed a sugar-free chewing gum(Coca trial), whereas theother was done after the subjects chewed 15 g of coca leaves(Coca⁺), with the order of theCoca andCoca⁺ trials being randomized.Blood samples were taken at rest, before (R₁) and after 1-h chewing(R₂), and during the 5th, 15th,30th, and 60th min of exercise. They were analyzed for hematocrit,hemoglobin concentration, red blood cell count, plasma proteins, andfor the fluid regulatory hormones, including plasma catecholamines [norepinephrine (NE) and epinephrine], renin, argininevasopressin, and the atrial natriuretic peptide (ANP). During thecontrol trial (Coca),from R₁ toR₂, there was no significantchange in hematologic, hormonal, and cardiovascular status except for asmall increase in plasma NE. In contrast, it can be calculated thatcoca chewing at rest induced a significant hemoconcentration(3.8 ± 1.3% in blood and 7.0 ± 0.7% in plasmavolume), increased NE and MAP, and reduced plasma ANP. Chewing cocabefore exercise reduced the body fluid shifts but enhanced HR responseduring exercise. These effects were not accompanied by changes in NE,epinephrine, renin, and arginine vasopressin plasma levels. Incontrast, plasma ANP response to exercise was lower during theCoca⁺ trial, suggesting thatcentral cardiac filling was reduced by coca use. It is likely that thereduction in body fluid volumes is a major contributing factor to thehigher HR at any given time of exercise after coca chewing.

     

A molecular phylogeny for the Drosophila melanogaster subgroup and the problem of polymorphism data

Drosophila melanogaster belongs to a closely related group of eight species collectively known as the melanogaster subgroup; all are native to sub-Saharan Africa and islands off the east coast of Africa. The phylogenetic relationships of most species in this subgroup have been well documented; however, the three most closely related species, D. simulans, D. sechellia, and D. mauritiana, have remained problematic from a phylogenetic standpoint as no data set has unambiguously resolved them. We present new DNA sequence data on the nullo and Serendipity-alpha genes and combine them with all available nuclear DNA sequence data; the total data encompass 12 genes and the ITS of rDNA. A methodological problem arose because nine of the genes had information on intraspecific polymorphisms in at least one species. We explored the effect of inclusion/exclusion of polymorphic sites and found that it had very little effect on phylogenetic inferences, due largely to the fact that 82% of polymorphisms are autapomorphies (unique to one species). We have also reanalyzed our previous DNA-DNA hybridization data with a bootstrap procedure. The combined sequence data set and the DNA-DNA hybridization data strongly support the sister status of the two island species, D. sechellia and D. mauritiana. This at least partially resolves what had been a paradox of parallel evolution in these two species.      

Chromosomal localization of a tandemly repeated DNA sequence in Trifolium repens L

INTRoDUCTIoNlYho1iumrePensL,whiteclover,isaneconomicallyimportantplantspeciesintemperatepastures.Asbrieflyreportedby[1],ithas16pairsofchromosomes(2n=32).Asyet,nodetailedcytologicalexaminationofthisspecies,suchasC-banding,hasbeenrep0rted.Inthelastdecade,thetechnique0fC-bandinghasbeenusedt0examinehighlyrepeatedsequencesinplantchrom0s0mesandhasprovidedausefultoolf0rtheanalysis0fcyt0geneticstructureincr0pplants[2-71.Inplants,thechr0m0s0mall0calizationofhighlyrepeatedDNAsequencesbyinsituhybr…     

Interspecific and intraspecific comparisons of the period locus in the Drosophila willistoni sibling species

The period (per) locus has received much attention in molecular evolution studies because it is one of the best studied "behavioral genes" and because it offers insight into the evolution of repetitive sequences. We studied most of the coding region of per in Drosophila willistoni and confirmed previously observed patterns of conservation and divergence among distantly related species. Five regions are so highly diverged that they cannot be aligned, whereas a region encompassing the PAS domain is very conserved. Structural and nucleotide polymorphism patterns in the willistoni group are not the same as those observed in previously studied species. We sequenced the region homologous to the highly polymorphic threonine-glycine repeat of D. melanogaster in multiple strains of D. willistoni, as well as in other members of willistoni group, and found an unusual amount of conservation in this region. However, the next nonconserved region downstream in the sequence is quite variable and polymorphic for the number of repeated glycines. The glycine codon usage is significantly different in this glycine repeat as compared to other parts of the gene. We were able to plot the directionality of change in the glycine repeat region onto a phylogeny and find that the addition of glycines is the general trend with the diversification of the willistoni group.      

L’electromyographie du penis: Une nouvelle exploration du muscle lisse caverneux et de son controle neurologique?

The authors have investigated the electrical activity of corpus cavernous, first according to Wagner and Gerstenberg’ method, then, since one year, according to Stief method, in the basal state and following intracavernosal injection of vasoactive agents, or following various stimulation tests. They have found again the electrical activity described by these authors, but have been confronted with the difficulty in quantifying the data. Specially single potential analysis seems to them little reliable and reproducible for an objective interpretation. At this stage of their experience, they test two simpler criteria interpretation: the richness of the electrical activity, and the reactivity of the recording to various stimulations. Their preminary results suggest a correlation between those criteria and the state of the autonomic nervous system of the penis.