Neurohumoral Axis Research Articles

Diuretics in cardiac oedema.

Cardiogenic oedema results from an increase in capillary hydrostatic pressure (either pulmonary or systemic). This increase produces a reduction in the plasma colloidosmotic pressure-capillary pressure gradient, facilitating the accumulation of fluid in the interstitial space and reducing the circulating plasmatic volume. The administration of diuretics to patients with acute ventricular dysfunction has both haemodynamic and renal effects, and causes a reduction in extravascular fluid. In chronic heart failure, the use of diuretics may result in a haemodynamic improvement once the volaemia is reduced. However, in some patients diuretics may cause activation of the neurohumoral axis and consequently a transient haemodynamic deterioration.

Acute vasoconstrictor response to intravenous furosemide in patients with chronic congestive heart failure. Activation of the neurohumoral axis.

Hemodynamic and neurohumoral responses to acute diuretic therapy were measured in 15 patients with severe chronic heart failure given intravenous furosemide, 1.3 +/- 0.6 (SD) mg/kg body weight. Left ventricular pump function deteriorated by 20 minutes, as indicated by a fall in stroke volume index (27 +/- 8 to 24 +/- 7 mL/min X m2 body surface area, p less than 0.01) and an increase in left ventricular filling pressure (28 +/- 7 to 33 +/- 9 mm Hg, p less than 0.01). Increases occurred in heart rate (87 +/- 13 to 91 +/- 16 beats/min, p less than 0.01), mean arterial pressure (90 +/- 15 to 96 +/- 15 mm Hg, p less than 0.01), systemic vascular resistance (1454 +/- 394 to 1676 +/- 415 dynes X s X cm-5, p less than 0.01), plasma renin activity (9.9 +/- 8.5 to 17.8 +/- 16 ng/mL X h, p less than 0.05), plasma norepinephrine level (667 +/- 390 to 839 +/- 368 pg/mL, p less than 0.01), and plasma arginine vasopressin level (6.2 +/- 1.3 to 8.3 +/- 2.0 pg/mL, p less than 0.01). During the next 3.5 hours the patients had diuresis (2085 +/- 1035 mL) and the expected fall in filling pressure (28 +/- 7 to 22 +/- 10 mm Hg, p less than 0.01). Neurohumoral indicators also returned toward the control levels. Intravenous furosemide, in patients with severe chronic heart failure, is associated with acute pump dysfunction temporally related to activation of the neurohumoral axis.

The neurohumoral axis in congestive heart failure.

The incidence of congestive heart failure is increasing in the United States. This common syndrome is characterized not only by impaired ventricular function but also by an increase in some endogenous vasoconstrictor substances, including norepinephrine, angiotensin II, and arginine vasopressin. Although activation of the systems that release these substances is presumed to be compensatory (to maintain perfusion pressure during inadequate flow), the sympathetic nervous system, renin-angiotensin-aldosterone system, and arginine vasopressin may contribute to the pathogenesis of the syndrome. The excessive vasoconstriction present in heart failure likely produces a further burden on the failing myocardium. New strategies in therapy are being developed to counteract the activation of vasoconstrictor forces in congestive heart failure. Data indicate that selective blockade of the renin-angiotensin system is useful. Preliminary data suggest that inhibition of the sympathetic nervous system may be helpful, and inhibition of vasopressin in animals with heart failure is being studied. New and more selective therapy for heart failure may come from these studies.

Stress and metabolic control in diabetes: psychosomatic evidence and evaluation of methods.

Psychosomatic research findings correlating psychologic stress with diabetic control fail as yet to provide valid conclusions. Investigators have presented many contradictory findings. The two major pathways by which stress could affect control, a) changes in compliance behavior, and b) a neurohumoral axis, have not been clearly distinguished from each other. The study of adolescent cohorts is associated with the problem of heterogeneity, limiting the application of results to other diabetic populations. Methods of determining diabetic control have been incomplete and the definition and measurement of stress have major inadequacies for the analysis of such a complex psychosomatic problem. Existing evidence is comprehensively reviewed and evaluated. The authors use a modified definition of stress to construct a stress scale specific to pregnant diabetics.

Changes in total plasma content of electrolytes and proteins with maximal exercise.

To determine to what extent the increases in concentration of plasma proteins and electrolytes with short maximal work were a result of hemoconcentration, the changes in plasma volume and total content of the plasma constituents were simultaneously evaluated. The results obtained from six human subjects indicated that in comparison to preexercise values there was a net decrease in total content of plasma protein, sodium, and chloride in the first 2 min of the postexercise period, due primarily to a significant loss (13-15%) of plasma fluid. The total plasma potassium content was increased immediately after exercise but was significantly below the preexercise plasma content after 2 min of recovery.