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Biomedical subjects

Catherine F Notarius

Publications and source records attributed to Catherine F Notarius.

6 recordsLinked to original sources
PubMed2006

Caffeine attenuates early post-exercise hypotension in middle-aged subjects.

BACKGROUND: Sustained hypotension after an acute dynamic exercise bout is due primarily to peripheral vasodilation. We tested the hypothesis that adenosine-mediated vasodilation contributes to hypotension after exercise, by determining the effect of blocking its actions with caffeine. METHODS: Fourteen healthy middle-aged subjects (mean age = 51 +/- 3 years), cycled to peak effort on 2 study days, after a randomized double-blind intravenous infusion of caffeine (4 mg/kg) selective for adenosine receptor blockade, or vehicle. Both studies were performed after 72 h of caffeine abstinence. RESULTS: Infusion achieved 52.0 +/- 6.1 mumol/L caffeine in plasma. Significant reductions in mean and diastolic blood pressure (BP) were elicited by prior exercise on the vehicle day (from 93 +/- 2 to 85 +/- 2 mm Hg v from 79 +/- 2 to 73 +/- 3 mm Hg, respectively; both P < .05), but not after caffeine infusion. Systolic and mean BP, 10 min after exercise, were higher on the caffeine than on the vehicle day (by 9 +/- 3 and 6 +/- 2 mm Hg, respectively; P < .05), as was heart rate (HR) (100 +/- 5 v 93 +/- 4 beats/min; P < .05). CONCLUSIONS: These data suggest that endogenous adenosine contributes to early hypotension after exercise in healthy middle-aged subjects and underscore the importance of caffeine abstinence if BP or HR immediately after exercise is used to infer cardiovascular risk.

Biomarkers↗
PubMed2006

Caffeine prolongs exercise duration in heart failure.

BACKGROUND: Caffeine increases submaximal exercise performance in healthy young subjects; its effects on exercise tolerance in heart failure (HF) have not been characterized. METHODS AND RESULTS: To determine whether caffeine increases exercise tolerance in HF, caffeine (4 mg/kg intravenously, equivalent to 2 cups of coffee) or vehicle were infused into 10 treated HF patients (left ventricular ejection fraction 25 +/- 2 %), and 10 age-matched normal subjects (N) on 2 separate days in a double-blind, randomized, crossover design. We measured heart rate, blood pressure, and ventilation at rest and during graded cycling (15 W/minute) to peak effort. Peak oxygen consumption was unaffected in either group. Mean exercise time was unchanged in N (1,013 +/- 87 versus 988 +/- 107 seconds; P = .86) but was significantly increased by caffeine in HF (from 511 +/- 28 to 560 +/- 37 seconds; P = .004) despite an increase in peak minute ventilation (P < .05). Resting and peak blood pressures were higher after caffeine (P < .05) in HF, not N. CONCLUSION: Caffeine allows HF patients to exercise longer at peak effort.

Adult↗
PubMed2005

Exercise as an alternative to oral estrogen for amelioration of endothelial dysfunction in postmenopausal women.

BACKGROUND: Both exercise and postmenopausal estrogen therapy augment endothelial function. We hypothesized that their interaction would be additive. The study objectives were to determine in postmenopausal women (1) the effects of an acute bout of exercise on brachial artery endothelium-dependent flow-mediated vasodilation (FMD), (2) whether these responses to exercise are augmented by concurrent estrogen treatment, and (3) whether these 2 interventions, independently or together, achieve FMD values observed in premenopausal women. METHODS: In postmenopausal women (n = 13; age 54 +/- 2 [mean +/- SE] years), FMD was quantified during supine rest and again 60 minutes after treadmill exercise for 45 minutes at 60% V* O2max. Subjects were studied twice: before and after 4 weeks of oral estradiol. To obtain reference normal values, FMD was determined concurrently in 14 premenopausal (28 +/- 1 years) women under identical basal conditions. RESULTS: Flow-mediated vasodilation in postmenopausal women, markedly impaired when compared with premenopausal women (5.3% +/- 0.5% vs 12.1% +/- 1.5%, P < .01), was significantly increased by exercise (to 9.9% +/- 0.6%, P < .01). In contrast, after estrogen, FMD was augmented at rest (P < .01) but was not further enhanced after exercise (11.5% +/- 0.6% vs 9.9% +/- 0.5%, P = .3). Both interventions increased, independently, FMD to values in premenopausal women (P > .05). CONCLUSIONS: In postmenopausal women, both acute exercise and estrogen therapy normalize FMD. However, their effects are not additive, possibly because of redundancy of nitric oxide signaling pathways activated by these 2 interventions. When considered in the context of recent trials with adverse cardiovascular outcomes, these results reinforce the therapeutic potential of exercise as an alternative nonpharmacological intervention to estrogen in postmenopausal women with endothelial dysfunction.

Administration, Oral↗
PubMed2005

Hemodynamic after-effects of acute dynamic exercise in sedentary normotensive postmenopausal women.

OBJECTIVES: To determine, in sedentary normotensive postmenopausal women, the after-effects of exercise on systemic and regional hemodynamics, and whether changes in total peripheral conductance after exercise relate to changes in brachial artery flow-mediated vasodilation (FMD). METHODS: In 13 sedentary postmenopausal women, the blood pressure (BP), cardiac output, total peripheral resistance and total peripheral conductance, calf vascular resistance and FMD were measured during baseline rest, and again commencing 45 min after treadmill exercise. Fourteen premenopausal women completed the identical protocol to obtain reference values for the after-effects of exercise in healthy females. RESULTS: In postmenopausal women, exercise was followed by falls in systolic BP (P < 0.01) and diastolic BP (P < 0.001). BP did not fall after exercise in premenopausal women. In both groups the cardiac output (P < 0.01) increased and the calf vascular resistance (P < 0.01) and total peripheral resistance (P < 0.05) decreased after exercise, but resistance fell more (P < 0.05) in postmenopausal women. Baseline FMD was greater in premenopausal women (12.1 +/- 1.5 versus 5.3 +/- 1.3%, P < 0.01), and similar before and after exercise, whereas prior exercise nearly doubled the FMD of postmenopausal women (to 9.9 +/- 1.4%, P < 0.01). These increases in FMD correlated with baseline values (r = -0.75, P < 0.01) and with relative changes in total peripheral conductance (r = 0.72, P < 0.02). The latter relationship was absent in premenopausal women (r = -0.29). CONCLUSIONS: In postmenopausal women, acute dynamic exercise elicits sustained increases in FMD that could facilitate post-exercise hypotension in this population. These observations reinforce the concept of exercise as an important non-pharmacological intervention to modify cardiovascular risk in postmenopausal women.

Adult↗