Adrenergic Control of the Peripheral Circulation in Cardiomyopathic Hamsters with Heart Failure

Abstract

Adrenergic control of the peripheral circulation was studied in cardiomyopathic hamsters to determine if the functional status of terminal vascular sympathetic nerve endings is augmented in heart failure. Four groups of hamsters were studied: myopathic hamsters with heart failure (average age 296 days), myopathic hamsters without heart failure (average age 171 days), and two corresponding control groups of randomly bred hamsters matched for age. In hamsters with heart failure, the concentration of catecholamines in hearts, aortas, and femoral arteries was reduced compared with that in corresponding control hamsters. In myopathic hamsters without heart failure, the concentration of catecholamines was reduced in femoral arteries, but it was not reduced in hearts or aortas. Resting vascular resistance and vasoconstrictor responses to sympathetic nerve stimulation, norepinephrine, and angiotensin in the perfused hindquarters was reduced in hamsters with heart failure but not in myopathic hamsters without heart failure. These studies suggest that the functional status of terminal sympathetic nerve endings in blood vessels of the extremities is not augmented and may be reduced in this model of heart failure. Studies on other models of heart failure are needed to determine whether the absence of increased vascular catecholamines and the absence of augmented responses to sympathetic nerve stimulation are characteristic of heart failure in general or are unique to this model that has characteristics of highoutput failure.KEY WORDS catecholamines aorta femoral artery sympathetic nerve stimulation norepinephrine angiotensin• Myocardial norepinephrine stores are depleted and cardiac responses to sympathetic nerve stimulation are reduced in heart failure (1-5), but the status of sympathetic innervation of blood vessels in heart failure remains controversial. Several investigators have reported that reflex vasoconstrictor responses to exercise are increased in heart failure (6, 7), and Kramer et al. (8) have suggested that the amount of norepinephrine available for release from sympathetic nerve endings of resistance vessels in the extremities is augmented in heart failure. However, Hayduk and co-workers (9) normal or decreased in heart failure. Also, Higgins et al. (10) have demonstrated that reflex increases in vascular resistance during bilateral carotid artery occlusion are reduced in dogs with experimental heart failure. These studies have raised questions about the sympathetic control of the peripheral circulation in heart failure. There have been no reports in which vascular responses to direct sympathetic nerve stimulation have been obtained in heart failure and correlated with measurements of catecholamines in blood vessels to assess the status of sympathetic innervation of blood vessels.The present experiments were performed to study the adrenergic control of the peripheral circulation in the Syrian hamster (Mesocricetus auratus) with hereditary cardiomyopathy and congestive heart failure (11,12). Specifi...

Relationship between central hemodynamics and regional blood flow in normal subjects and in patients with congestive heart failure.

“…Vascular reactivity to norepinephrine and to nerve stimulation decreases in the animal preparation of congestive heart failure. 19 It is likely that "autoregulation," the mechanisms of which is not yet precisely defined,20 also plays an important role in the attenuation of changes in renal vascular resistance and flow as heart failure worsens.…”

The Contribution of Local Factors to the Elevated Venous Tone of Congestive Heart Failure

“…Recently, the concept of increased neurogenically mediated venous tone in heart failure has been questioned, and it has been implied that venous tone in heart failure may not be elevated (7). Similarly, the circulatory role of the sympathetic nervous system in heart failure has been questioned (8,9). Therefore, the purpose of these studies was to reevaluate the state of the systemic veins in heart failure especially in terms of the local factors that might contribute to alterations in venous tone.…”

Differences in the regulation of vascular resistance in guinea pigs with right and left heart failure.

“…In one study, for example, the reflex vasoconstrictor response to carotid occlusion was less in dogs with right heart failure than in normal dogs. 5 In two other studies reported from our own laboratory, the neurogenic influence, as estimated from the vasodilator response to sympathectomy, was not abnormally increased in hamsters with cardiomyopathy 6 or in dogs with right heart failure. 7 These observations have led us to consider the possibility that various types of heart failure might differ with regard to the relative importance of the factors regulating vascular resistance.…”