Kevin C Kregel

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In a recent study, we demonstrated that transmission from peripheral sympathetic nerves to vascular smooth muscles is strongest in the frequency band from 0.2 to 0.5 Hz in conscious rats. In contrast, sympathetic modulation of vasomotor tone in humans is suggested to be reflected in the power spectrum of arterial blood pressure in a frequency range centered(More)
Adult-onset, long-term caloric restriction (CR) prolongs maximum life span in laboratory rodents. However, the effect of this intervention on an organism's ability to cope with a physical challenge has not been explored. We investigated the influence of CR and aging on stress tolerance in old rats exposed to an environmental heating protocol on two(More)
Power spectrum analysis of arterial blood pressure (BP) and heart rate (HR) has been used to investigate autonomic nervous system activity. Sympathetic-mediated vasomotor tone has been attributed to the BP power at frequencies between 0.05 and 0.15 Hz in humans and dogs and between 0.2 and 0.8 Hz in rats. In contrast, it has been suggested that the(More)
The purpose of this study was to test the hypothesis that the cardiovascular and sympathoadrenal responses to acute environmental stress are attenuated by exercise training. Furthermore, we tested the hypothesis that the cardiovascular and sympathoadrenal responses to intracerebroventricular (ICV) administration of corticotropin-releasing factor (CRF) would(More)
To characterize the efferent pathway from the hypothalamic paraventricular nucleus (PVN) to peripheral autonomic neurons and finally to selected effector organs, we stimulated the PVN in 10 conscious rats at frequencies ranging from 0.05 to 2.0 Hz. Simultaneously, blood pressure, heart rate, splanchnic sympathetic nerve activity, and mesenteric artery blood(More)
The hemodynamic responses to vasoconstrictor agents are blunted during heating in anesthetized rats. It is unknown whether reflex neural responses to these agents are also altered during hyperthermia. Therefore, the purpose of this study was to determine the effect of hyperthermia on the hemodynamic and baroreflex-mediated sympathetic neural responses to(More)
Superoxide anion (O2*-) is increased throughout the arterial wall in atherosclerosis. The oxidative stress contributes to lesion formation and vascular dysfunction. In the present study, we tested the hypothesis that NAD(P)H oxidase-derived O2*- is increased in nodose sensory ganglia and sympathetic ganglia of apolipoprotein E deficient (apoE-/-) mice, an(More)
The purpose of this study was to determine if the arterial baroreceptor reflexes modulate the sympathocirculatory responses to acute heat stress. To address this, arterial pressure, heart rate, mesenteric and renal blood flow velocity (Doppler flow probes), arterial plasma norepinephrine, and colonic temperature were measured before and during whole body(More)
Aging alters cellular responses to both heat and oxidative stress. Thiol-mediated metabolism of reactive oxygen species (ROS) is believed to be important in aging. To begin to determine the role of thiols in aging and heat stress, we depleted liver glutathione (GSH) by administering l-buthionine sulfoximine (BSO) in young (6 mo) and old (24 mo) Fisher 344(More)
Two male (10-13 kg) patas monkeys (Erythrocebus patas) were implanted with bilateral thermodes to control hypothalamic temperature. Animals were restrained in primate chairs and instrumented to yield hypothalamic (THYPO), colonic (Tc), and mean skin (Tsk) temperatures, chest sweat rate (mSW), and heart rate (HR). THYPO was monitored using a thermocouple(More)