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2023 JAN 28 (NewsRx) -- By a News Reporter-Staff News Editor at Obesity, Fitness & Wellness Week -- New research on Peptide Proteins - Posterior Pituitary Hormones is the subject [...]

The heart of a fetus undergoing stress inside the uterus may adapt by releasing a substance known as atrial natriuretic peptide (ANP) to change cardiac output. An example of intrauterine stress is hypoxia, or lack of oxygen to the fetus. Researchers used sheep fetuses to study the effect of changes in pressure in the heart atrium. Induced pressure changes in the atrium caused higher than normal levels of ANP to be released. High levels of arginine vasopressin and plasma renin activity were also observed in response to increases in atrial pressure. Changes in heart rate did not seem to influence ANP levels.

Fluid restriction is usually a standard part of treatment for bacterial meningitis for several reasons. Patients with meningitis, which involves inflammation of the membrane surrounding the brain, tend to have elevated levels of antidiuretic hormone (ADH; arginine vasopressin), and treatment of that condition is fluid restriction. (The effect of ADH is to decrease urine secretion, increase blood volume and blood pressure.) However, no study has shown that fluid restriction to levels two thirds or three fourths of that needed for maintenance can prevent the syndrome. It is possible that elevated ADH levels are not inappropriate for the status of patients with meningitis. This idea was tested by either restricting fluids or by giving maintenance plus replacement fluids to 19 patients with bacterial meningitis or meningitis due to other causes. Eleven of 12 patients with bacterial meningitis and 3 of 6 patients with aseptic meningitis had blood ADH levels that were elevated in comparison to those in healthy adults. The nine patients in the restricted group received an average of two thirds of maintenance requirements, while those in the added-fluid group received an average of 1.42-fold over maintenance levels. After 24 hours of treatment, arginine vasopressin levels were significantly lower in patients who received additional fluid. This was related to the amount of sodium administered, although blood sodium levels did not change significantly. The study suggests that low blood volume associated with fever and vomiting in meningitis triggers ADH secretion, and ADH levels dropped when increased sodium intake, which increases fluid retention, corrected low blood volume. The study suggests that in the absence of the syndrome of inappropriate ADH, indicated by low blood sodium levels, children with meningitis may be given full maintenance fluids low in salt plus replacement fluids containing normal salt levels. (Consumer Summary produced by Reliance Medical Information, Inc.)

To study the relation between Plasma atrial natriuretic peptide (ANP) and cardiac pressure, and to assess the pathophysiologic significance of ANP in water and electrolyte metabolism, the changes in plasma levels of ANP and arginine vasopressin (AVP) were examined in 11 pattern with mitral stenosis who underwent permbneous transvenous mitrald valvuplasty and compared with the changes in the renin-angiotensin-aldosterone system and renal function. immediately after valvuloplasty, plasma ANP levels decreased significantly with a concomitant decrease in mean pressures in the left atrium, the pulmonary artery and the right atrium. plasma ANP levels decreased tO the normal range in 4 of the 6 patients with normal sinus rhythm, while all 5 patients with atrial fibrillation had higher levels despite a similar degree of decrease in atrial pressure. There were significant positive correlations between plasma ANP levels and the mean left atrial pressure (r = 0.61, p, Atrial natriuretic peptide (ANP) is a substance originally isolated from the human atrium (either of the chambers of the heart that receive blood from the body and lungs prior to delivering it to the ventricles), that has now been purified and synthesized. ANP has effects on sodium and water retention, as well as on blood vessels, and it is possible that it is released in response to increased pressure in the atria, such as could occur during heart failure, when blood is not pumped efficiently. If atrial stretch is significantly involved in increasing ANP levels, then reduction of atrial pressure should decrease them, and this was assessed in 11 patients with faulty mitral valves (the valve between the left atrium and left ventricle) who underwent a corrective procedure. Blood was taken before the procedure known as percutaneous transvenous mitral valvuloplasty (valve surgery or restoration), and at intervals afterward until 24 hours had passed. Blood was assayed for its levels of ANP, AVP (arginine vasopressin, a hormone apparently detected by cells in the atrium), renin, and aldosterone. These latter substances are known to control sodium and water retention, and to reflect renal (kidney) function. Results showed a decrease in the average left atrial pressure, but not the right, after valvuloplasty. ANP levels were elevated in nine patients before the procedure, and dropped to lower than control levels immediately afterward. Although lower, ANP levels remained above normal for the five patients who experienced atrial fibrillation (random, irregular contractions of the atria). Levels of ANP were correlated with left atrial pressure, right atrial pressure, and pulmonary arterial pressure (the artery through which blood flows from the right ventricle to the lungs). AVP levels increased temporarily after valvuloplasty, then returned to the same level as before surgery. Renin and aldosterone levels increased 30 minutes after valvuloplasty, as did measures of renal function. Overall, the results indicate that the heart's atrium responds to a reduction in pressure by reducing ANP secretion, which, in turn, alters water and sodium metabolism. It also appears that atrial fibrillation, or abnormal atrial contraction in itself, can stimulate ANP secretion. (Consumer Summary produced by Reliance Medical Information, Inc.)

Why do female orcas (killer whales), pilot whales, and humans--unlike females of other species--continue to live long after their ability to reproduce ends? The theory of evolution says that their [...]

The present study analyzes the hemodynamics of intracardiac occlusive priods during balloon mitral or aortic valvuloplasty and compares them with immediate plasma levels of atrial natriuretic factor (ANF), vasopressin and renin activity. Forty-nine patients were studied; 33 of them had mitral stenosis and 16 had aortic stenosis. The mean age was 52 [+ or -] 17 years. During dilations pressures were monitored from the ascending aorta and left atrium. Plasma levels of ANF, vasopressin and renin were serially determined at baseline, after diagnostic procedures, within 15 to 30 seconds after the first 2 occlusive dilations, and 1 and 7 hours later. There were no significant changes in plasma renin throughout the study stages. ANF and vasopressin significantly increased after the dilations. These hormonal changes were related to the significant hemodynamic changes observed during intracardiac occlusion. The left atrial pressure correlated directly and significantly (r = 0.54, p [is less than]0.001) with plasma ANF levels throughout the conditions. On the other hand, the plasma vasopressin also correlated (r = 0.76, p [is less than]0.001) with systemic pressure in an exponential fashion. These findings show that abrupt releases of ANF and vasopressin occur immediately after intracardiac occlusive periods as a response to the acute and transient hemodynamic changes observed., Homeostatic response refers to the adjustment of the body to maintain equilibrium which is sustained via feedback and regulation mechanisms. A study of the response to abrupt physiological changes was performed by the measurement of plasma levels of atrial natriuretic factor (ANF), vasopressin and renin activity prior to and at intervals after balloon valvuloplasty was performed on 49 patients. These three hormones are involved in the control of blood pressure by their effect on the blood vessels. Thirty-three patients had stenosis (narrowing or closing) of the mitral valve in the heart and 16 had stenosis of the aorta, the main arterial vessel leading from the heart. Balloon angioplasty involves the insertion of a tube with a small balloon at its end into the artery; the balloon is inflated at the point of closure to open the vessel and increase blood flow. Dilations were monitored from the ascending aorta and from the left atrium. Baseline blood level measurements of the hormones were first taken at 15 to 30 seconds after the procedure and again at one to seven hours after the procedure, and were then plotted against systemic blood pressure. Changes in concentrations of these hormones were observed to correlate with changes in blood flow produced by the angioplasty; abrupt release of ANF and vasopressin occurred. Increase in ANF was found to be proportional and elevated vasopressin concentrations correlated exponentially. No change in renin levels was recorded. The effect of vasopressin release may provide rapid control of arterial pressure and thus account for the patients' good general tolerance of the balloon valvuloplasty. However, the release of higher concentrations of ANF would likely counteract the effects of vasopressin. The benefits and the apparent contradictory behavior of these mechanisms need to be better understood and further research is recommended.

Why is the serum sodium low? EXPRESS STOP Settings for SIADH: An antidiuretic hormone (ADH)-producing malignancy is the prime setting for the syndrome of inappropriate antidiuretic hormone production (SIADH). The [...]