Vascular Reactivity to Catecholamines in Rats Adapted to Trauma

Hruza, Z; Bw, Zweifach

doi:10.1097/00005373-196905000-00007

Cited by 11 publications

(5 citation statements)

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“…These studies support an age-related reduction in cardiac p,-adrenoreceptor-mediated responses, which may explain the reduction in maximal CO and HR to adrenergic stimuli. In addition, a-adrenergic-mediated vasopressive thresholds for NE in the splanchnic vascular bed were found to be higher in mature than in younger animals (27).…”

Section: Discussionmentioning

confidence: 87%

Cardiovascular hyporesponsiveness to norepinephrine, propranolol and nitroglycerin in portal-hypertensive and aged rats

Polio

Sieber

Lerne³

et al. 1993

Hepatology

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Most studies testing vasoactive agents in portal-hypertensive rats have been performed in young animals. To assess age-related changes in hemodynamic responses to adrenergic stimuli, we examined (a) responsiveness to norepinephrine (0.14 to 12.0 micrograms.kg-1.min-1) in young (3-mo-old) and aged (9-mo-old) sham-operated and portal-hypertensive rats and (b) response to propranolol (2 and 10 mg.kg-1 body wt), nitroglycerin (3.6 mg.kg-1.min-1) or saline solution in aged portal-hypertensive rats. Aged rats exhibited significantly (p < 0.05) smaller responses to norepinephrine with regard to increases in mean arterial pressure and superior mesenteric arterial vascular resistance, irrespective of portal hypertension. Portal hypertension alone potentiated this reduced response in aged animals and was associated with cardiovascular hyporesponsiveness to norepinephrine in young rats. Portal pressure was significantly (p < 0.05) lower in aged sham-operated rats than in young sham-operated rats over a wide range of norepinephrine doses. Portal-hypertensive aged rats showed significantly (p < 0.05) lower heart rates. Furthermore, systemic and splanchnic cardiovascular responses to propranolol and nitroglycerin mediated by the sympathetic nervous system were decreased or negligible in aged rats, compromising the portal-hypotensive effects of these drugs. In summary, aged rats express diminished cardiovascular responsiveness to adrenergic stimuli. Therefore age should be considered an important factor in studies evaluating pharmacological agents for the treatment of portal hypertension.

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Section: Discussionmentioning

confidence: 87%

Cardiovascular hyporesponsiveness to norepinephrine, propranolol and nitroglycerin in portal-hypertensive and aged rats

Polio

Sieber

Lerne³

et al. 1993

Hepatology

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“…This up ward shift may be due to reduced vasocon strictive response to sympathetic stimula tion. The sensitivity of arterioles to catechol amines decreases with age [8]. The cerebral vessels of young rats react to hypoxia and hypocapnia more rapidly than those of older ones [6].…”

Section: Discussionmentioning

confidence: 97%

Effect of Aging on Collateral Circulation via Pial Anastomoses in Cats

et al. 1988

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The effect of aging on collateral circulation via pial anastomoses after middle cerebral artery occlusion was investigated in young and aged cats. The reduction of blood flow and electroencephalography power were greater and collateral vessel resistance was higher in the aged group than the young group. Electroencephalography power after the occlusion was correlated with collateral resistance and blood flow in the two groups. These results suggest that collateral function deteriorates with aging and the high vulnerability to ischemic insult in aged brain may be caused in part by the poor collateral function.

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“…Using the in vivo rat mesoappendix tech nique, Hruza and Zweifach [1967] found a reduced reactivity of ar terioles to catecholamines as a function of age. While catecholamine metabolism was not directly assessed, the same investigators concluded that reduced vascular reactivity was not a result of altered catecholamine disposition with age.…”

Section: Discussionmentioning

confidence: 97%

Vascular Contraction: Effect of Age and Extracellular Calcium

Cohen¹,

Berkowitz²

1976

J Vasc Res

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Contractile responses to norepinephrine, serotonin and potassium chloride were determined in vitro for aortas from rats 1, 2, 3 and 12 months of age. Responses were measured under conditions of optimum length (3 cm) and resting tension (1 g). Aortic response to a maximum concentration of norepinephrine was greatest for vessels from 3-month-old rats. For all three agonists, aortas from 12-month-old rats contracted less than aortas from 2-month-old rats. The role of calcium in aortic contraction also varied with age. For rats 1–2 months of age, serotonin and potassium chloride-induced contractions were highly dependent on extracellular calcium, while norepinephrine-induced contraction showed only a slight dependence on extracellular calcium. In 12-month-old rats, all agonists were dependent on extracellular calcium for contraction. For serotonin and norepinephrine, the ability of muscle to contract in calcium-free media was decreased with age. Although the mechanism for such an altered dependence of aortic contraction on calcium has not been established, it is proposed that the utilization of extracellular calcium for contraction is not only agonist- but also age-dependent.

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Vascular Reactivity to Catecholamines in Rats Adapted to Trauma

Cited by 11 publications

References 0 publications

Cardiovascular hyporesponsiveness to norepinephrine, propranolol and nitroglycerin in portal-hypertensive and aged rats

Cardiovascular hyporesponsiveness to norepinephrine, propranolol and nitroglycerin in portal-hypertensive and aged rats

Effect of Aging on Collateral Circulation via Pial Anastomoses in Cats

Vascular Contraction: Effect of Age and Extracellular Calcium

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