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R H Cox

Publications and source records attributed to R H Cox.

219 records · Page 13Linked to original sources
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Exercise training attenuates stress-induced hypertension in the rat.

The ability of exercise training to block the generation of hypertension produced by chronic stress in the borderline hypertensive rat was tested. Twenty-three male borderline hypertensive rats, F1 offspring of spontaneously hypertensive and Wistar-Kyoto rats, were divided into three groups. Two groups (8 rats per group) were subjected to 2 hours of daily, predictable, uncontrollable tail shock for 12 weeks. One of these groups was also given 2 hours of daily swim stress (exercise trained). A third group served as a maturation control and received neither intervention (n = 7). After 12 weeks of stress, direct recording of blood pressure verified the pattern observed with tail cuff: shock only group, 180/118 +/- 3/3 mm Hg; exercise-trained and shocked group, 166/108 +/- 4/2 mm Hg; and control group, 160/98 +/- 6/4 mm Hg (mean +/- SEM). Systolic and diastolic blood pressures in the shock only group were significantly higher than in both the other groups (p less than 0.05). The control group differed from the exercise-trained and shocked group only in diastolic BP (p less than 0.05). During a short-term stress session plasma norepinephrine levels in the exercise-trained and shocked group were significantly lower than those in the shock only group (555 +/- 56 vs 776 +/- 84 pg/ml; p less than 0.05). These results indicate that an alteration of autonomic function resulted from the exercise training, but its contribution to the resistance of the exercise-trained and shocked rats to stress-induced hypertension is unclear.

Analysis of Variance↗
PubMedDate not supplied

The metabolism and excretion of 14C-styrene oxide-glutathione adducts administered to the winter flounder, Pseudopleuronectes americanus, a marine teleost. Identification of the corresponding S-cysteine derivatives as major urinary metabolites.

The metabolism and excretion of intramuscularly administered 14C-glutathione conjugates of styrene oxide (Ia and IIa) were studied in the winter flounder at three dose levels. The various radiolabeled thioether metabolites excreted were separated by reverse-phase high pressure liquid chromatography, and identified and quantitated by cochromatography with synthetic standards. The urine was the major excretion route for radioactivity derived from the glutathione conjugates (up to 90%) at each dose level (1.0, 3.9, and 24.4 mg/fish) studied. The corresponding cysteine derivatives (Ic, IIc) were the major urinary metabolites although the N-acetylcysteine derivatives (Id, IId), or mercapturic acids, were also present in significant amounts at each dose and excretion interval examined. Unchanged glutathione conjugates of styrene oxide were the major radioactive constituents of 24-hr bile samples from the treated flounder, although significant amounts of the cysteinylglycine (Ib, IIb), cysteine, and N-acetylcysteine derivatives were also present in bile. Bile was a minor excretory route relative to urine. The oxidation of 14C-styrene to styrene 7,8-oxide by the cytochrome P-450-dependent monooxygenase system of hepatic microsomes of winter flounder was also demonstrated; likewise, styrene was converted to the diastereomeric glutathione conjugates of styrene 7,8-oxide by 9,000g supernatant fractions of flounder liver supplemented with glutathione. This study demonstrated that flounder liver can convert styrene to glutathione conjugates to styrene oxide and that mercapturic acid biosynthesis occurs after parenteral administration of a xenobiotic-glutathione adduct to this marine species, although the major urinary metabolites were the cysteine conjugates rather than the anticipated mercapturic acid derivatives.

Acetylcysteine↗