Effect of aging on renal blood flow velocity during static exercise

Momen, Afsana; Leuenberger, Urs A.; Handly, Brian; Sinoway, Lawrence I.

doi:10.1152/ajpheart.00959.2003

Cited by 34 publications

(35 citation statements)

References 32 publications

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“…With regard to aging, there is growing evidence that renal vasoconstriction in response to isometric handgrip (i.e., sympathoexcitatory stimulus) is enhanced in older adults (34,42). To our knowledge, we are the first to document renal responses to the CPT in older humans.…”

Section: Discussionmentioning

confidence: 89%

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Effect of healthy aging on renal vascular responses to local cooling and apnea

Patel

Mast

Sinoway

et al. 2013

Journal of Applied Physiology

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Patel HM, Mast JL, Sinoway LI, Muller MD. Effect of healthy aging on renal vascular responses to local cooling and apnea. J Appl Physiol 115: 90 -96, 2013. First published May 2, 2013 doi:10.1152/japplphysiol.00089.2013.-Sympathetically mediated renal vasoconstriction may contribute to the pathogenesis of hypertension in older adults, but empirical data in support of this concept are lacking. In 10 young (26 Ϯ 1 yr) and 11 older (67 Ϯ 2 yr) subjects, we quantified acute hemodynamic responses to three sympathoexcitatory stimuli: local cooling of the forehead, cold pressor test (CPT), and voluntary apnea. We hypothesized that all stimuli would increase mean arterial blood pressure (MAP) and renal vascular resistance index (RVRI) and that aging would augment these effects. Beat-bybeat MAP, heart rate (HR), and renal blood flow velocity (from Doppler) were measured in the supine posture, and changes from baseline were compared between groups. In response to 1°C forehead cooling, aging was associated with an augmented MAP (20 Ϯ 3 vs. 6 Ϯ 2 mmHg) and RVRI (35 Ϯ 6 vs. 16 Ϯ 9%) but not HR. In older adults, there was a positive correlation between the cold-induced pressor response and forehead pain (R ϭ 0.726), but this effect was not observed in young subjects. The CPT raised RVRI in both young (56 Ϯ 13%) and older (45 Ϯ 8%) subjects, but this was not different between groups. Relative to baseline, end-expiratory apnea increased RVRI to a similar extent in both young (46 Ϯ 14%) and older (41 Ϯ 9%) subjects. During sympathetic activation, renal vasoconstriction occurred in both groups. Forehead cooling caused an augmented pressor response in older adults that was related to pain perception. cold face test; renal blood flow; vasoconstriction; peripheral chemoreflex; noxious cooling THE KIDNEY IS A VITAL ORGAN for salt and water homeostasis and receives ϳ20% of cardiac output in resting humans (60). Furthermore, the renal vasculature is innervated by sympathetic nerves that allow for alpha adrenergic-mediated vasoconstriction during times of stress (i.e., exercise and orthostasis) (6, 43). As such, acute adjustments in renal blood flow importantly contribute to whole-body fluid balance and blood pressure control. It follows that chronic impairments in this process (e.g., enhanced water reabsorption and/or enhanced vasoconstriction) predispose an individual to hypertension. Considering that aging itself is a risk factor for hypertension (44,67), and glomerular filtration rate declines with age (12,14), baseline impairments in renal function combined with sympathetic activation may negatively affect the elderly. Therefore, a better understanding of the renal circulation in older adults may have clinical relevance. However, there is currently little experimental data (42, 61) regarding the effect of healthy aging on renal vasoconstriction during sympathoexcitatory stress.Cold temperatures are seasonally experienced in most regions of the world. The compensatory physiological responses to cold involve the sympathetic nervous ...

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Section: Discussionmentioning

confidence: 89%

“…Therefore, a better understanding of the renal circulation in older adults may have clinical relevance. However, there is currently little experimental data (42,61) regarding the effect of healthy aging on renal vasoconstriction during sympathoexcitatory stress.…”

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confidence: 99%

Effect of healthy aging on renal vascular responses to local cooling and apnea

Patel

Mast

Sinoway

et al. 2013

Journal of Applied Physiology

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“…All healthy volunteers were nonsmoking, normotensive, and on no medication. Of the 11 healthy volunteers, 5 individuals were also studied in a prior report (12).…”

Section: Study Populationmentioning

confidence: 99%

“…All healthy volunteers were nonsmoking, normotensive, and on no medication. Of the 11 healthy volunteers, 5 individuals were also studied in a prior report (12).Seven RTX patients with preserved native kidneys were recruited from the renal transplantation clinic at the Hershey Medical Center. Transplant surgeries were performed 7-14 mo before the study.…”

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confidence: 99%

Renal vascular response to static handgrip exercise: sympathetic vs. autoregulatory control

Momen

Bower

Leuenberger³

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

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Static exercise causes activation of the sympathetic nervous system, which results in increased blood pressure (BP) and renal vascular resistance (RVR). The question arises as to whether renal vasoconstriction that occurs during static exercise is due to sympathetic activation and/or related to a pressure-dependent renal autoregulatory mechanism. To address this issue, we monitored renal blood flow velocity (RBV) responses to two different handgrip (HG) exercise paradigms in 7 kidney transplant recipients (RTX) and 11 age-matched healthy control subjects. Transplanted kidneys are functionally denervated. Beat-by-beat analyses of changes in RBV (observed via duplex ultrasound), BP, and heart rate were performed during HG exercise in all subjects. An index of RVR was calculated as BP/RBV. In protocol 1, fatiguing HG exercise (40% of maximum voluntary contraction) led to significant increases in RVR in both groups. However, at the end of exercise, RVR was more than fourfold higher in control subjects than in the RTX group (88 vs. 20% increase over baseline; interaction, P Ͻ 0.001). In protocol 2, short bouts of HG exercise (15 s) led to significant increases in RVR at higher workloads (50 and 70% of maximum voluntary contraction) in the control subjects (P Ͻ 0.001). RVR did not increase in the RTX group. In conclusion, we observed grossly attenuated renal vasoconstrictor responses to exercise in RTX subjects, in whom transplanted kidneys were considered functionally denervated. Our results suggest that renal vasoconstrictor responses to exercise in conscious humans are mainly dependent on activation of a neural mechanism.kidney; blood flow; autoregulation; handgrip; vasoconstriction; transplant DURING EXERCISE, THE SYMPATHETIC nervous system is activated, and this results in increases in heart rate (HR), blood pressure (BP), and peripheral vasoconstriction. As part of this process, renal vasoconstriction occurs and serves to maintain BP as well as to redistribute blood flow to the contracting skeletal muscle bed.Of note, the observed increase in renal vascular resistance (RVR) is associated with an increase in arterial pressure. Thus the question arises as to whether renal vasoconstriction that occurs during static exercise is due to sympathetic activation and/or related to a pressure-dependent renal autoregulatory mechanism. To address this issue, we monitored renal hemodynamic responses during two different handgrip exercise paradigms in a group of kidney transplant recipients (RTX) and in age-matched healthy control subjects. Previous reports (7,8,16) suggest that transplanted kidneys remain functionally denervated for several months after transplantation. In studies measuring tissue norepinephrine in rat kidney grafts (7), researchers found grossly diminished norepinephrine levels compared with native kidneys 9 mo after transplantation. Similarly, necropsy specimens from human renal allografts demonstrate a reduction in sympathetic ganglia synaptic density 3 yr after transplantation (16). In addition, the resea...

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“…For the renal artery (RA) flow during exercise, Momen et al (12)(13)(14) observed a transient response during short bouts of handgrip exercise using ultrasound Doppler. They found that renal vasoconstriction is evoked by mechanoreflex-mediated sympathetic vasoconstriction during handgrip exercise.…”

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confidence: 99%

Differential arterial blood flow response of splanchnic and renal organs during low-intensity cycling exercise in women

Endo

Suzuki

Nagahata

et al. 2008

American Journal of Physiology-Heart and Circulatory Physiology

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To investigate the regional hemodynamic responses of abdominal arteries at the onset of exercise and to focus on their transient responses, eight female subjects (21-30 yr) performed ergometer cycling exercise at 40 W for 4 min in a semi-supine position. Mean blood velocities (MBVs) in the right renal (RA), superior mesenteric (SMA), and splenic (SA) arteries were measured by pulsed echo-Doppler ultrasonography, with beat-by-beat measurements of heart rate (HR) and mean arterial pressure (MAP). The vascular resistance index (RI) of each artery was calculated from MBV/MAP. MAP (76 +/- 9 to 83 +/- 8 mmHg at 4 min) and HR (60 +/- 7 to 101 +/- 9 beats/min at 4 min) increased during exercise (P < 0.05). The MBV of RA and SA rapidly decreased after the onset of exercise (30 s; -19 +/- 5% and -19 +/- 12%, respectively), reaching -27 +/- 7% and -27 +/- 15% at the end of exercise (P < 0.05). RI did not change during the initial 30 s of exercise, reflecting a reduction in MAP, and increased toward the end of the exercise (+55 +/- 21% and +59 +/- 39%, respectively). In contrast, both the MBV and RI in the SMA remained constant throughout the exercise. The results indicate that, whereas the responses of renal and splenic vessels changed similarly throughout the protocol, the vascular response of SMA that mainly supplies blood to the intestinal tract was unchanged during exercise. We, therefore, conclude that low-intensity cycling exercise resulted in differential blood flow responses in arteries supplying the abdominal organs.

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Effect of aging on renal blood flow velocity during static exercise

Cited by 34 publications

References 32 publications

Effect of healthy aging on renal vascular responses to local cooling and apnea

Effect of healthy aging on renal vascular responses to local cooling and apnea

Renal vascular response to static handgrip exercise: sympathetic vs. autoregulatory control

Differential arterial blood flow response of splanchnic and renal organs during low-intensity cycling exercise in women

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