Altered regional blood flow responses to submaximal exercise in older rats

2004 ◽  
Vol 96 (1) ◽  
pp. 81-88 ◽  
Author(s):  
Timothy I. Musch ◽  
Kevin E. Eklund ◽  
K. Sue Hageman ◽  
David C. Poole
Keyword(s):  
Blood Flow ◽  
Regional Blood Flow ◽  
Muscle Blood Flow ◽  
Submaximal Exercise ◽  
Brown Norway ◽  
Maximal Aerobic Capacity ◽  
Fischer 344 ◽  
Hindlimb Muscles ◽  
Effects Of Aging ◽  
Small And Large Intestine

Maximal aerobic capacity and the ability to sustain submaximal exercise (Ex) declines with advancing age. Whether altered muscle blood flow (BF) plays a mechanistic role in these effects remains to be resolved. The present investigation determined the effects of aging on the hemodynamic and regional BF response to submaximal Ex in rats. Heart rate (HR), mean arterial pressure (MAP), and BF to different organs (kidneys, splanchnic organs, and 28 hindlimb muscles) were determined at rest and during submaximal treadmill Ex (20 m/min, 5% grade) with radiolabeled microspheres in young (Y; 6-8 mo old, 339 ± 8 g, n = 9) and old (O; 27-29 mo old, 504 ± 18 g, n = 7) Fischer 344 × Brown Norway rats. Results demonstrated that HR, MAP, and BF to the pancreas, small and large intestine, and total hindlimb musculature were similar between Y and O rats at rest. BF to the kidneys, spleen, and stomach were 33, 60, and 43% lower, respectively, in O compared with Y rats. BF to the total hindlimb musculature increased ( P < 0.05) during Ex and was similar for both Y and O rats (Y: 16 ± 3 to 124 ± 7 vs. O: 20 ± 3 to 137 ± 12 ml·min-1·100 g-1). However, in O vs. Y rats, BF was reduced in 6 (highly oxidative) and elevated in 8 (highly glycolytic) of the 28 individual hindquarter muscles or muscle parts examined ( P < 0.05). During Ex, BF to the spleen and stomach decreased ( P < 0.05) from rest in Y rats, whereas BF decreased in the kidneys, pancreas, spleen, stomach, as well as the small and large intestines of O rats. In conclusion, these data demonstrate that, despite similar increases in total hindlimb BF in Y and O rats during submaximal Ex, there is a profound BF redistribution from highly oxidative to highly glycolytic muscles.

Effects of aging on vasoconstrictor and mechanical properties of rat skeletal muscle arterioles

2002 ◽  
Vol 282 (5) ◽  
pp. H1843-H1854 ◽  
Author(s):  
Judy Muller-Delp ◽  
Scott A. Spier ◽  
Michael W. Ramsey ◽  
Lisa A. Lesniewski ◽  
Anthony Papadopoulos ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Skeletal Muscle ◽  
Blood Flow ◽  
Muscle Blood Flow ◽  
Intraluminal Pressure ◽  
Aged Rats ◽  
Mechanical Stiffness ◽  
Fischer 344 ◽  
Effects Of Aging ◽  
Gastrocnemius Muscles

Exercise capacity and skeletal muscle blood flow during exercise are reduced with advancing age. This reduction in blood flow capacity may be related to increased reactivity of skeletal muscle resistance vessels to vasoconstrictor stimuli. The purpose of this study was to test the hypothesis that aging results in increased vasoconstrictor responses of skeletal muscle resistance arterioles. First-order (1A) arterioles (90–220 μm) from the gastrocnemius and soleus muscles of young (4 mo) and aged (24 mo) Fischer-344 rats were isolated, cannulated, and pressurized via hydrostatic reservoirs. Vasoconstriction in response to increases in norepinephrine (NE; 1 × 10−9–1 × 10−4 M) and KCl (20–100 mM) concentrations and increases in intraluminal pressure (10–130 cmH2O) were evaluated in the absence of flow. Responses to NE and KCl were similar in both soleus and gastrocnemius muscle arterioles from young and aged rats. In contrast, active myogenic responses to changes in intraluminal pressure were diminished in soleus and gastrocnemius arterioles from aged rats. To assess whether alterations in the mechanical properties of resistance arterioles underlie altered myogenic responsiveness, passive diameter responses to pressure and mechanical stiffness were evaluated. There was no effect of age on the structural behavior (passive pressure-diameter relationship) or stiffness of arterioles from either the soleus or gastrocnemius muscles. These results suggest that aging does not result in a nonspecific decrease in vasoconstrictor responsiveness of skeletal muscle arterioles. Rather, aging-induced adaptations of vasoreactivity of resistance arterioles appear to be limited to mechanisms that are uniquely involved in the signaling of the myogenic response.

Sympathetic neural influences on muscle blood flow in rats during submaximal exercise

1988 ◽  
Vol 65 (1) ◽  
pp. 434-440 ◽  
Author(s):  
D. F. Peterson ◽  
R. B. Armstrong ◽  
M. H. Laughlin
Keyword(s):  
Blood Flow ◽  
Muscle Blood Flow ◽  
Sympathetic Innervation ◽  
Flow Distribution ◽  
Sympathetic Nerves ◽  
Submaximal Exercise ◽  
Fiber Types ◽  
Blood Flows ◽  
Hindlimb Muscles ◽  
Hindlimb Muscle

These experiments were designed to estimate the involvement of the sympathetic innervation in regulation of hindlimb muscle blood flow distribution among and within muscles during submaximal locomotory exercise in rats. Blood flows to 32 hindlimb muscles and 13 other selected tissues were measured using the radiolabeled microsphere technique, before exercise and at 0.5, 2, 5, and 15 min of treadmill exercise at 15 m/min. The two groups of rats studied were 1) intact control, and 2) acutely sympathectomized (hindlimb sympathectomy accomplished by bilateral section of the lumbar sympathetic chain and its connections to the spinal cord at L2-L3). There were no differences in total hindlimb muscle blood flow among the two groups during preexercise or at 30 s or 2 min of exercise. However, flow was higher in eight individual muscles at 2 min of exercise in the sympathectomized rats. At 5 and 15 min of exercise there was higher total hindlimb muscle blood flow in the denervated group compared with control. These differences were also present in many individual muscles. Our results suggest that 1) sympathetic nerves do not exert a net influence on the initial elevations in muscle blood flow at the beginning of exercise, 2) sympathetic nerves are involved in regulating muscle blood flow during steady-state submaximal exercise in conscious rats, and 3) these changes are seen in muscles of all fiber types.

Impact of aging on muscle blood flow in chronic heart failure

2005 ◽  
Vol 99 (2) ◽  
pp. 505-514 ◽  
Author(s):  
Kevin E. Eklund ◽  
K. Sue Hageman ◽  
David C. Poole ◽  
Timothy I. Musch
Keyword(s):  
Heart Failure ◽  
Blood Flow ◽  
Chronic Heart Failure ◽  
Muscle Blood Flow ◽  
Muscle Fibers ◽  
Left Ventricular ◽  
Exercise Intolerance ◽  
Brown Norway ◽  
Hindlimb Muscles ◽  
Fast Twitch

Chronic heart failure (CHF) is manifested principally in the elderly population. Therefore, to understand the causes of exercise intolerance in CHF patients, it is imperative to resolve the effects of aging on muscle blood flow (BF) in CHF. To address this issue, we determined the muscle BF response to submaximal treadmill exercise (20 m/min, 5% grade) in young (YCHF: 6–8 mo, 412 ± 11 g, n = 11) and old (OCHF: 27–29 mo, 494 ± 10 g, n = 8) Fischer 344 × Brown Norway rats with similar degrees of myocardial infarction-induced left ventricular (LV) dysfunction [resting LV end-diastolic pressure: YCHF = 24 ± 2, OCHF = 22 ± 2 mmHg; derivative of LV pressure over time: YCHF = 5,168 ± 285; OCHF = 5,050 ± 165 mmHg/s; lung weight normalized to body weight: YCHF = 9.14 ± 0.72; OCHF = 8.21 ± 0.29 mg/g (all P > 0.05)]. The exercising heart rate response was blunted in OCHF compared with YCHF rats (YCHF = 454 ± 8, OCHF = 395 ± 9 beats/min; P < 0.05). BF (radiolabeled microspheres) to the total hindlimb musculature and to each of the 28 individual muscles examined was similar between YCHF and OCHF rats under resting conditions. During exercise, BF to five of the hindlimb muscles that normally possess a majority of slow-twitch oxidative and fast-twitch oxidative glycolytic muscle fibers increased significantly less (−25 to −42%) for OCHF compared with YCHF rats. In contrast, BF to 14 of the hindlimb muscles that normally possess a majority of fast-twitch glycolytic muscle fibers was increased (+22 to +337%) for OCHF vs. YCHF rats, which contributed to a greater mass-specific total hindlimb BF response in OCHF rats (YCHF = 78 ± 5, OCHF = 100 ± 11 ml·min−1·100 g−1; P < 0.05) and coincided with greater reductions in BF to the kidneys and splanchnic organs during exercise in OCHF vs. YCHF. In conclusion, there appears to be a profound age-related redistribution of BF from the highly oxidative to the highly glycolytic muscles of the hindlimb during exercise in OCHF compared with YCHF rats. This phenomenon is qualitatively similar to that reported previously for healthy young and old rats.

Neural control of glucose uptake by skeletal muscle after central administration of NMDA

1995 ◽  
Vol 268 (2) ◽  
pp. R492-R497 ◽  
Author(s):  
C. H. Lang ◽  
M. Ajmal ◽  
A. G. Baillie
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Glucose Uptake ◽  
Neural Control ◽  
Plasma Insulin ◽  
Regional Blood Flow ◽  
Muscle Blood Flow ◽  
Whole Body ◽  
Glucose Disposal ◽  
Central Administration

Intracerebroventricular injection of N-methyl-D-aspartate (NMDA) produces hyperglycemia and increases whole body glucose uptake. The purpose of the present study was to determine in rats which tissues are responsible for the elevated rate of glucose disposal. NMDA was injected intracerebroventricularly, and the glucose metabolic rate (Rg) was determined for individual tissues 20-60 min later using 2-deoxy-D-[U-14C]glucose. NMDA decreased Rg in skin, ileum, lung, and liver (30-35%) compared with time-matched control animals. In contrast, Rg in skeletal muscle and heart was increased 150-160%. This increased Rg was not due to an elevation in plasma insulin concentrations. In subsequent studies, the sciatic nerve in one leg was cut 4 h before injection of NMDA. NMDA increased Rg in the gastrocnemius (149%) and soleus (220%) in the innervated leg. However, Rg was not increased after NMDA in contralateral muscles from the denervated limb. Data from a third series of experiments indicated that the NMDA-induced increase in Rg by innervated muscle and its abolition in the denervated muscle were not due to changes in muscle blood flow. The results of the present study indicate that 1) central administration of NMDA increases whole body glucose uptake by preferentially stimulating glucose uptake by skeletal muscle, and 2) the enhanced glucose uptake by muscle is neurally mediated and independent of changes in either the plasma insulin concentration or regional blood flow.

Regional circulatory responses to hypocapnia and hypercapnia in bar-headed geese

1986 ◽  
Vol 250 (3) ◽  
pp. R499-R504 ◽  
Author(s):  
F. M. Faraci ◽  
M. R. Fedde
Keyword(s):  
Blood Flow ◽  
Regional Blood Flow ◽  
Muscle Blood Flow ◽  
Pectoral Muscle ◽  
Blood Flows ◽  
Arterial Blood ◽  
Blood Flow Reduction ◽  
Extreme Altitude ◽  
Anser Indicus ◽  
O2 Delivery

To investigate mechanisms that may allow birds to tolerate extreme high altitude (hypocapnic hypoxia), we examined the effects of severe hypocapnia and moderate hypercapnia on regional blood flow in bar-headed geese (Anser indicus), a species that flies at altitudes up to 9,000 m. Cerebral, coronary, and pectoral muscle blood flows were measured using radioactive microspheres, while arterial CO2 tension (PaCO2) was varied from 7 to 62 Torr in awake normoxic birds. Arterial blood pressure was not affected by hypocapnia but increased slightly during hypercapnia. Heart rate did not change during alterations in PaCO2. Severe hypocapnia did not significantly alter cerebral, coronary, or pectoral muscle blood flow. Hypercapnia markedly increased cerebral and coronary blood flow, but pectoral muscle blood flow was unaffected. The lack of a blood flow reduction during severe hypocapnia may represent an important adaptation in these birds, enabling them to increase O2 delivery to the heart and brain at extreme altitude despite the presence of a very low PaCO2.

scholarly journals The Effects of Aging on Indices of Oxidative Stress and Apoptosis in the Female Fischer 344/Nnia X Brown Norway/BiNia Rat Heart

2013 ◽  
Vol 7 (1) ◽  
pp. 113-121 ◽  
Author(s):  
Jacqueline Fannin ◽  
Kevin M. Rice ◽  
Srininvas Thulluri ◽  
Ravi Kumar Arvapalli ◽  
Paulette Wehner ◽  
...  
Keyword(s):  
Superoxide Anion ◽  
Caspase 3 ◽  
Nitrosative Stress ◽  
Descriptive Study ◽  
Female Rats ◽  
Brown Norway ◽  
Rodent Models ◽  
Fischer 344 ◽  
Stress Markers ◽  
Effects Of Aging

Oxidative-nitrosative stress may play a role in age-associated cardiovascular disease as implied by recent studies.However, limited research has been conducted using aged female rodent models. In this study, we examined hearts obtained from 6-, 26-, and 30-month old female Fischer 344/Nnia x Brown Norway/BiNia (F344xBN) rats in order to examine how aging affects levels of cardiac oxidative-nitrosative stress and apoptosis. Oxidative (superoxide anion and 4-HNE) and nitrosative (protein nitrosylation) stress markers were increased 180 ± 17 %, 110 ± 3 %, and 14 ± 2 %, respectively in 30-month hearts compared to the hearts of 6-month female rats. Coincident with these changes in oxidative-nitrosative stress, aging was also found to be associated with increases in the number of Tdt-mediated dUTP nick labeling (TUNEL)-positive cardiomyocytes, alterations in the Bax/Bcl-2 ratio, and elevated cleavage of caspase-3. Regression analysis demonstrates significant correlation in the age-associated changes markers of oxidative–nitrosative stress with changes in apoptotic signaling. The findings from this descriptive study imply that age-associated increases in mitochondrial-mediated apoptosis may be associated with the increase in oxidative-nitrosative stress in the aging F344xBN female heart.

Regional blood flow in conscious resting rats determined by microsphere distribution

1993 ◽  
Vol 74 (1) ◽  
pp. 203-210 ◽  
Author(s):  
I. Kuwahira ◽  
N. C. Gonzalez ◽  
N. Heisler ◽  
J. Piiper
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Regional Blood Flow ◽  
Sampling Technique ◽  
Organ Blood Flow ◽  
Sprague Dawley ◽  
Blood Flows ◽  
Hindlimb Muscles ◽  
Acclimation Period ◽  
The Difference

To determine organ blood flow in the resting state, a box was designed to keep conscious untrained rats minimally disturbed. Blood pressure, heart rate, and organ blood flow, determined by the microsphere distribution and reference sampling technique, were measured in 11 Sprague-Dawley rats. After an acclimation period, 15-microns-diameter microspheres labeled with 113Sn were infused into the ascending aorta, a reference blood sample was withdrawn from the caudal artery, and organ blood flows were computed according to standard procedures. The average values of heart rate (365 beats/min) and blood flow to the brain (45 ml.min-1.100 g-1) and hindlimb muscles (15 ml.min-1.100 g-1) were significantly lower than most values reported earlier, whereas splanchnic blood flow was significantly higher (106 ml.min-1.100 g-1). Blood flow to the soleus muscle, which is considered the most active for postural maintenance, was relatively high (99 ml.min-1.100 g-1). The combination of low skeletal muscle and high visceral blood flows observed in these experiments suggests a low sympathetic tone, which is consistent with the low level of circulating catecholamines also observed in this study. It is hypothesized that the difference between our present and previous results is a lower level of stress, attributable to a more complete acclimation to the experimental environment.

Altered Regional Blood Flow Responses to Submaximal Exercise in Older Rats.

2004 ◽  
Vol 15 (1) ◽  
pp. 28-29
Author(s):  
T I Musch ◽  
K E Eklund ◽  
K S Hageman ◽  
D C Poole
Keyword(s):  
Blood Flow ◽  
Regional Blood Flow ◽  
Submaximal Exercise

scholarly journals Effects of Aging and Renin‐Angiotensin System (RAS) Blockade on the Intra‐renal RAS in Older Fischer 344 X Brown Norway Rats

2008 ◽  
Vol 22 (S1) ◽  
Author(s):  
Sherry O Kasper ◽  
Shea Gilliam‐Davis ◽  
Leanne Groban ◽  
Christy S Carter ◽  
William E Sonntag ◽  
...  
Keyword(s):  
Renin Angiotensin System ◽  
Brown Norway ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Fischer 344 ◽  
Effects Of Aging ◽  
Norway Rats

Influence of heat stress on exercise-induced changes in regional blood flow in sheep

1983 ◽  
Vol 55 (6) ◽  
pp. 1916-1923 ◽  
Author(s):  
A. W. Bell ◽  
J. R. Hales ◽  
R. B. King ◽  
A. A. Fawcett
Keyword(s):  
Blood Flow ◽  
Skin Blood Flow ◽  
Regional Blood Flow ◽  
Respiratory Muscles ◽  
Fold Increase ◽  
Respiratory Alkalosis ◽  
Upper Respiratory Tract ◽  
Hindlimb Muscles ◽  
Exercise Induced ◽  
Induced Changes

Radioactive microspheres were used to measure cardiac output and blood flow to most major tissues in sheep at rest and during treadmill exercise (3- to 6-fold increase in metabolic rate for 30 min) in thermoneutral (TN) [dry bulb temperature (Tdb) = 16 degrees C, wet bulb temperature (Twb) = 12 degrees C] and mildly hot (MH) (Tdb = 40 degrees C, Twb = 23 degrees C) environments. During exercise, rectal temperature increased more under MH than under TN conditions; exercise-induced changes in the major central cardiovascular parameters were unaffected by MH. Exercise in TN caused mild hypocapnia, and in MH, severe respiratory alkalosis. Skin blood flow in the torso decreased during exercise in TN and MH. Extremity skin blood flow was increased by heat but not exercise. Exercise-induced increases in flows to respiratory muscles and upper respiratory tract tissues were greatly enhanced in MH. Exercise caused large increases in blood flow to fore- and hindlimb muscles, which were less in MH than in TN. Effects of MH on exercise-induced changes in flow to these and other tissues (e.g., abdominal viscera and adipose tissue) are discussed in terms of the conflicting requirements of energy expenditure and body temperature regulation during exercise in sheep and other species, particularly humans.

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