Dietary calcium intake and Renin Angiotensin System polymorphisms alter the blood pressure response to aerobic exercise: a randomized control design

BACKGROUND: Dietary calcium intake and the renin angiotensin system (RAS) regulate blood pressure (BP) by modulating calcium homeostasis. Despite similar BP regulatory effects, the influence of dietary calcium intake alone and combined with RAS polymorphisms on the BP response following acute aerobic exercise (i.e., postexercise hypotension) has not been studied. Thus, we examined the effect of dietary calcium intake and selected RAS polymorphisms on postexercise hypotension. METHODS: Subjects were men (n = 50, 43.8 ± 1.3 yr) with high BP (145.3 ± 1.5/85.9 ± 1.1 mm Hg). They completed three experiments: non-exercise control and two cycle bouts at 40% and 60% of maximal oxygen consumption (VO(2)max). Subjects provided 3 d food records on five protocol-specific occasions. Dietary calcium intake was averaged and categorized as low (<880 mg/d = LowCa) or high (≥ 880 mg/d = HighCa). RAS polymorphisms (angiotensin converting enzyme insertion/deletion, ACE I/D; angiotensin II type 1 receptor, AT(1)R A/C) were analyzed with molecular methods. Genotypes were reduced from three to two: ACE II/ID and ACE DD; or AT(1)R AA and AT(1)R CC/AC. Repeated measure ANCOVA tested if BP differed among experiments, dietary calcium intake level and RAS polymorphisms. RESULTS: Systolic BP (SBP) decreased 6 mm Hg after 40% and 60% VO(2)max compared to non-exercise control for 10 h with LowCa (p < 0.01), but not with HighCa (p ≥ 0.05). Under these conditions, diastolic BP (DBP) did not differ between dietary calcium intake levels (p ≥ 0.05). With LowCa, SBP decreased after 60% VO(2)max versus non-exercise control for 10 h among ACE II/ID (6 mm Hg) and AT(1)R AA (8 mm Hg); and by 8 mm Hg after 40% VO(2)max among ACE DD and AT(1)R CC/CA (p < 0.01). With HighCa, SBP (8 mm Hg) and DBP (4 mm Hg) decreased after 60% VO(2)max compared to non-exercise control for 10 h (p < 0.05), but not after 40% VO(2)max (p ≥ 0.05). CONCLUSION: SBP decreased after exercise compared to non-exercise control among men with low but not high dietary calcium intake. Dietary calcium intake interacted with the ACE I/D and AT(1)R A/C polymorphisms to further modulate postexercise hypotension. Interactions among dietary calcium intake, exercise intensity and RAS polymorphisms account for some of the variability in the BP response to exercise

The effects of nutritional supplementation throughout an endurance run on leucine kinetics during recovery

This study determined the effect of nutritional supplementation throughout endurance exercise on whole-body leucine kinetics (leucine rate of appearance [Ra], oxidation [Ox], and nonoxidative leucine disposal [NOLD]) during recovery. Five trained men underwent a 2-h run at 65% VO2max, during which a carbohydrate (CHO), mixed protein-carbohydrate (milk), or placebo (PLA) drink was consumed. Leucine kinetics were assessed during recovery using a primed, continuous infusion of 1-13C leucine. Leucine Ra and NOLD were lower for milk than for PLA. Ox was higher after milk-supplemented exercise than after CHO or PLA. Although consuming milk during the run affected whole-body leucine kinetics, the benefits of such a practice for athletes remain unclear. Additional studies are needed to determine whether protein supplementation during exercise can optimize protein utilization during recovery. © 2007 Human Kinetics, Inc

Dietary protein intake impacts human skeletal muscle protein fractional synthetic rates after endurance exercise

This investigation evaluated the physiological impact of different dietary protein intakes on skeletal muscle protein synthesis postexercise in endurance runners. Five endurance-trained, male runners participated in a randomized, crossover design diet intervention, where they consumed either a low (0.8 g/kg; LP)-, moderate (1.8 g/kg; MP)-, or high (3.6 g/kg; HP)-protein diet for 4 wk. Diets were designed to be eucaloric with carbohydrate, fat, and protein approximating 60, 30, and 10%; 55, 30, and 15%; and 40, 30, and 30% for LP, MP, and HP, respectively. Substrate oxidation was assessed via indirect calorimetry at 3 wk of the dietary interventions. Mixed-muscle protein fractional synthetic rate (FSR) was measured after an endurance run (75 min at 70% V̇o2 peak) using a primed, continuous infusion of [2H5]phenylalanine. Protein oxidation increased with increasing protein intake, with each trial being significantly different from the other (P less than 0.01). FSR after exercise was significantly greater for LP (0.083%/h) and MP (0.078%/h) than for HP (0.052%/h; P less than 0.05). There was no difference in FSR between LP and MP. This is the first investigation to establish that habitual dietary protein intake in humans modulates skeletal muscle protein synthesis after an endurance exercise bout. Future studies directed at mechanisms by which level of protein intake influences skeletal muscle turnover are needed

Chemo-enzymatic synthesis of heteroyohimbine alkaloid stereoisomers

Total synthesis of glycosylated seco-iridoid stereoisomers allows the identification and bypassing of the stereoselectivity of early steps in monoterpene indole alkaloid biosynthesis

Aza-Tryptamine Substrates in Monoterpene Indole Alkaloid Biosynthesis

Biosynthetic pathways can be hijacked to yield novel compounds by introduction of novel starting materials. Here we have altered tryptamine, which serves as the starting substrate for a variety of alkaloid biosynthetic pathways, by replacing the indole with one of four aza-indole isomers. We show that two aza-tryptamine substrates can be successfully incorporated into the products of the monoterpene indole alkaloid pathway in Catharanthus roseus. Use of unnatural heterocycles in precursor-directed biosynthesis, in both microbial and plant natural product pathways, has not been widely demonstrated, and successful incorporation of starting substrate analogs containing the aza-indole functionality has not been previously reported. This work serves as a starting point to explore fermentation of aza-alkaloids from other tryptophan- and tryptamine-derived natural product pathways