Whole-body protein synthesis in growing barrows: diurnal and day-to-day variation and the effect of site of tracer infusion and sampling

Abstract

. 1998. Whole-body protein synthesis in growing barrows: diurnal and dayto-day variation and the effect of site of tracer infusion and sampling. Can. J. Anim. Sci. 78: 575-585. In the first experiment, two catheters were placed in one of three sites for infusion and sampling (vena cava and vena cava with 7 cm between catheter tips, VC/VC, n = 5; right ventricle and atrium, RV/RA, n = 5; anterior aorta and left ventricle, AA/LV, n = 4) to determine the effect of site on the measurement of CO 2 and leucine kinetics. Pigs received a 6-h continuous i.v. infusion of NaH 13 CO 3 (1.45 µmol h -1 kg -1 , preceded by a priming dose of 2.05 µmol kg -1 ) and of L[1-13 C]leucine (9.7 µmol h -1 kg -1 , preceded by a priming dose of 9.7 µmol kg -1 ), the following day. No effect (P > 0.10) of site was observed on NaH 13 CO 3 recovery rate, leucine irreversible loss rate (leucine ILR) and leucine used for protein synthesis (LS). A tendency (P < 0.10) for increased leucine oxidation (LO) was observed with the VC/VC compared to the RV/RA sites. In the second experiment, six growing barrows with catheters in the VC/VC site were infused as earlier with NaH 13 CO 3 and L[1-13 C]leucine for three different 6h periods (12:00 to 18:00 h, first day; 20:00 to 02:00 h, night; 12:00 to 18:00 h, second day) to determine the diurnal and day-to-day variation of CO 2 and leucine kinetics. No effect (P > 0.10) of period was observed on NaH 13 CO 3 recovery rate, leucine ILR and LS. The LO was lower (P < 0.05) on the second day compared with the first day (day-to-day variation) while similar (P > 0.10) LO was observed between the first day and night (diurnal variation). Together, these results indicate that 1) the VC/VC site can be used for L[1-13 C]leucine and NaH 13 CO 3 infusions, 2) NaH 13 CO 3 recovery studies can be performed either the day preceding or following the measurement of substrate and 3) protein synthesis estimated from a 6-h infusion period can be extrapolated to the 24 h periods under conditions of frequent feeding.Key words: Pigs, leucine, protein synthesis, tracer techniques, diurnal variation Roy, N., Lapierre, H., Estrada, R. et Bernier, J. F. 1998. Synthèse protéique de l'organisme entier chez les porcs en croissance: variation diurne, quotidienne et l'effet de sites d'infusion et de prélèvement du traceur. Can. J. Anim. Sci. 78: 575-585. Dans la première expérience, deux cathéters ont été placés dans un des sites sélectionnés (veine cave et veine cave avec 7 cm entre les extrémités des cathéters, VC/VC, n = 5; ventricule et oreillette droits, RV/RA, n = 5; aorte antérieure et ventricule gauche, AA/LV, n = 4) pour vérifier l'effet du site de perfusion et de prélèvement sur les cinétiques du CO 2 et de la leucine. Les porcs ont été perfusés i.v. durant 6 h avec du NaH 13 CO 3 (1,45 µmol h -1 kg -1 , précédé d'une dose d'amorçage de 2,05 µmol kg -1 ) et avec de la L-[1-13 C] leucine (9,7 µmol h -1 kg -1 , précédé d'une dose d'amorçage de 9,7 µmol kg -1 ), le lendemain. Aucun effet (P > 0,10) des sites n'a été observé sur l...

Whole-body protein metabolism and plasma profiles of amino acids and hormones in growing barrows fed diets adequate or deficient in lysine

“…The IE of leucine and KIC were analyzed according to the procedure of Calder and Smith (1988), with the minor modifications described previously (Roy et al 1998) using a gas-chromatograph (Model 6890, Hewlett-Packard, Montreal, QC) coupled to a quadrupole mass spectrometer (Models 5971 and 5973, Hewlett-Packard, Montreal, QC). Analysis of the IE of CO 2 in exhaust air was performed as described by Roy et al (1998) using an isotope ratio mass spectrometer (Model SIRA 12, VG, Manchester, UK).…”

“…Feed intake was recorded daily and BW was determined weekly. On day 5, following a 12-h fast, pigs were anesthetized to allow the placement of two catheters in the vena cava with tips 7 cm from each other (Roy et al 1998). …”

“…On day 16, pigs (34.6 ± 1.8 kg) were moved from the metabolic cages to the respiratory chambers for stable isotope infusions (Roy et al 1998). On day 17, a continuous infusion (1.66 µmol h -1 kg -1 ) of NaH 13 CO 3 (99 atom percent; MSD Isotopes, Pointe Claire, QC) preceded by a priming dose of 2.35 µmol kg -1 (equivalent to 85 min of infusion; Wolfe 1992) was given in the catheter placed near the right atrium.…”

“…Exhaust air from each chamber was collected into a modified anesthesia bag (10 L) for 2-min periods at -2, -1, 0, 1, 2, 3, 4, 5 and 6 h relative to the beginning of the infusion to determine the isotopic enrichment (IE) of CO 2 . At the same time, whole-body O 2 consumption (VO 2 ) and CO 2 production (VCO 2 ) were measured and calculated as described by Roy et al (1998).…”

“…At the end of the L-[1-13 C]leucine infusion, pigs were euthanized by exsanguination under anesthesia and the positions of the catheters were verified. Isotope solutions were individually prepared as described by Roy et al (1998).…”