Age-Associated Differences in Guinea Pig Myocardial Na&lt;sup&gt;+&lt;/sup&gt;, K&lt;sup&gt;+&lt;/sup&gt;-ATPase Activity and Ouabain Inhibition and in Mg&lt;sup&gt;2+&lt;/sup&gt;-ATPase Activity

Kroening, Bruce; Weintraub, Michael

doi:10.1159/000137432

Pharmacology

1980

DOI: 10.1159/000137432

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Age-Associated Differences in Guinea Pig Myocardial Na+, K+-ATPase Activity and Ouabain Inhibition and in Mg2+-ATPase Activity

Bruce Kroening¹,

Michael Weintraub²

Abstract: The influence of age on activity of cardiac Mg²⁺-ATPase and Na⁺, K⁺-ATPase from guinea pigs was studied. Tissue homogenates and Nal-washed membranes were prepared from the heart tissue of 10- to 12-day-old or > 12-month-old male guinea pigs. Tissue homogenates from the young animals had significantly greater enzyme activities than those from the older. Na⁺, K⁺-ATPase activity in young tissue preparations was less inhibited by ouabain than in older tissue p… Show more

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Cited by 7 publications

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“…In addition to anatomical changes of arterioles, other likely factors contributing to greater peripheral vascular resistance in the elderly hypertensive men include age-related alterations in cellular cation transport 25 -** and peripheral vascular /3-adrenergic desensitization, 27 resulting in relatively unopposed a-adrenergic responses to catecholamines. Indeed, the lower heart rate in the elderly hypertensive men in the control state and following graded LBNP in the present study likely reflects cardiovascular /3-adrenergic receptor down-regulation associated with aging.…”

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Effect of advancing age on cardiopulmonary baroreceptor function in hypertensive men.

Sowers¹,

Mohanty²

1987

Hypertension

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SUMMARY Blood pressure, heart rate, forearm vascular resistance, and hormonal responses to graded lower body negative pressure were investigated in 15 hypertensive men younger than 55 years of age (mean age, 44 ± 2 years) and 13 comparably hypertensive men older than 55 years of age (mean age, 63 ± 2 years). Baseline forearm vascular resistance was greater in the elderly group compared with the younger hypertensive men. However, forearm vascular resistance responses to selective unloading of low pressure cardiopulmonary baroreceptors were similar in the two groups. This finding suggests that normal vascular responses to the unloading of cardiopulmonary baroreceptors are preserved in subjects with advancing age and mild to moderate hypertension. Baseline plasma norepinephrine levels, as well as norepinephrine responses to lower body negative pressure, were comparable in the two groups. This finding suggests that, unlike normotensive subjects, essential hypertensive subjects do not have an age-related increase in sympathetic nervous system activity. (Hypertension 10: 274-279, 1987) KEY WORDS • cardiopulmonary baroreceptors • aging • norepinephrine A T H E R O S C L E R O S I S and other senescent/ \ changes in the carotid sinus region and the A. \ . aortic arch area have been reported to lead to impairment of high pressure baroreceptor function. '~3 That high pressure baroreceptor sensitivity is diminished with aging is evidenced by decreased bradycardia in response to pressor doses of phenylephrine.' Baroreceptor reflexes exert control over medullary vasomotor centers to modulate sympathetic nervous system activity, and the decline of high pressure baroreceptor and, perhaps, low pressure cardiopulmonary baroreceptor sensitivity 45 with aging probably contributes to the increased secretion of norepinephrine (NE) reported in normotensive subjects.6 " 10 This concept is supported by the observation that simultaneously increased sympathetic activity in several vascular beds occurs during inhibition of high pressure baroreceptor reflex activity." Furthermore, decreased high pressure baroreceptor reflex sensitivity is a characteristic observed in young to middle-aged patients with essential hypertension, 12 in whom the extent of the reflex abnormality is correlated with elevations of plasma NE. However, several recent studies 13 ' 14 have reported that plasma NE increases with age in normotensive subjects but not in subjects with essential hypertension. These recent observations suggest the possibility that receptor sensitivity of low pressure cardiopulmonary baroreceptors may not be diminished with increasing age in essential hypertensive persons.The present study was designed to compare the hormonal and hemodynamic responses in middle-aged and elderly patients with essential hypertension following selective activation of low pressure cardiopulmonary reflexes through graded lower body negative pressure (LBNP). Subjects and MethodsTwenty-eight men with mild to moderate essential hypertension were studied. Fifteen o...

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Effect of advancing age on cardiopulmonary baroreceptor function in hypertensive men.

Sowers¹,

Mohanty²

1987

Hypertension

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Quantification in crude homogenates of rat myocardial Na+, K+-and Ca2+-ATPase by K+ and Ca2+-dependent pNPPase. Age-dependent changes

Larsen

Kjeldsen

1995

Basic Res Cardiol

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Assays for complete quantification of Na+, K(+)- and Ca(2+)-ATPase in crude homogenates of rat ventricular myocardium by determination of K(+)- and Ca(2+)-dependent p-nitrophenyl phosphatase (pNPPase) activities were evaluated and optimized. Using these assays the total K(+)- and Ca(2+)-dependent pNPPase activities in ventricular myocardium of 11-12 week-old rats were found to be 2.98 +/- 0.10 and 0.29 +/- 0.02 mumol x min-1 x g-1 wet wt. (mean +/- SEM) (n = 5), respectively. Coefficient of variance of interindividual determinations was 7 and 12%, respectively. The total Na+, K(+)- and Ca(2+)-ATPase concentrations were estimated to 2 and 10 nmol x g-1 wet wt., respectively. Evaluation of a putative developmental variation revealed a biphasic age-related change in the rat myocardial Ca(2+)-dependent pNPPase activity with an increase from birth to around the third week of life followed by a decrease. By contrast, the K(+)-dependent pNPPase activity of the rat myocardium showed a decrease from birth to adulthood. It was excluded that the changes were simple outcome of variations in water and protein content of myocardium. Expressed per heart, the K(+)- and Ca(2+)-dependent pNPPase activity gradually increased to a plateau. The present assay for Na+, K(+)-ATPase quantification has the advantage over [3H] ouabain binding of being applicable on the ouabain-resistant rat myocardium, and is more simple and rapid than measurements of K(+)-dependent 3-O-methylfluorescein phosphatase (3-O-MFPase) in crude tissue homogenates. Furthermore, with few modifications the pNPPase assay allows quantification of Ca(2+)-ATPase on crude myocardial homogenates.(ABSTRACT TRUNCATED AT 250 WORDS)

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Salt sensitivity and systemic hypertension in the elderly

Zemel¹,

Sowers²

1988

The American Journal of Cardiology

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Age-Associated Differences in Guinea Pig Myocardial Na<sup>+</sup>, K<sup>+</sup>-ATPase Activity and Ouabain Inhibition and in Mg<sup>2+</sup>-ATPase Activity

Cited by 7 publications

References 0 publications

Effect of advancing age on cardiopulmonary baroreceptor function in hypertensive men.

Effect of advancing age on cardiopulmonary baroreceptor function in hypertensive men.

Quantification in crude homogenates of rat myocardial Na+, K+-and Ca2+-ATPase by K+ and Ca2+-dependent pNPPase. Age-dependent changes

Salt sensitivity and systemic hypertension in the elderly

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