Cardiac output during exercise is related to plasma atrial natriuretic peptide but not to central venous pressure in humans.

New Findings: What is the central question of this study? Is cardiac output during exercise dependent on central venous pressure? What is the main finding and its importance? The increase in cardiac output during both rowing and running is related to preload to the heart, as indicated by plasma atrial natriuretic peptide, but unrelated to central venous pressure. The results indicate that in upright humans, central venous pressure reflects the gravitational influence on central venous blood rather than preload to the heart.

Abstract: We evaluated the increase in cardiac output (CO) during exercise in relationship to central venous pressure (CVP) and plasma arterial natriuretic peptide (ANP) as expressions of preload to the heart.

Histamine and the regulation of body weight.

Energy intake and expenditure is regulated by a complex interplay between peripheral and central factors. An exhaustive list of peptides and neurotransmitters taking part in this complex regulation of body weight exists. Among these is histamine, which acts as a central neurotransmitter.

Erythropoietin treatment elevates haemoglobin concentration by increasing red cell volume and depressing plasma volume.

Erythropoietin (Epo) has been suggested to affect plasma volume, and would thereby possess a mechanism apart from erythropoiesis to increase arterial oxygen content. This, and potential underlying mechanisms, were tested in eight healthy subjects receiving 5000 IU recombinant human Epo (rHuEpo) for 15 weeks at a dose frequency aimed to increase and maintain haematocrit at approximately 50%. Red blood cell volume was increased from 2933 +/- 402 ml before rHuEpo treatment to 3210 +/- 356 (P < 0.

Increased susceptibility to diet-induced obesity in histamine-deficient mice.

Background And Aim: The neurotransmitter histamine is involved in the regulation of appetite and in the development of age-related obesity in mice. Furthermore, histamine is a mediator of the anorexigenic action of leptin. The aim of the present study was to investigate a possible role of histamine in the development of high-fat diet (HFD)-induced obesity.

The CSF and arterial to internal jugular venous hormonal differences during exercise in humans.

Strenuous exercise increases the cerebral uptake of carbohydrate out of proportion to that of oxygen, but it is unknown whether such enhanced carbohydrate uptake is influenced by the marked endocrine response to exercise. During exhaustive exercise this study evaluated the a-v differences across the brain (a-v diff) of hormones that could influence its carbohydrate uptake (n= 9). In addition, neuroendocrine activity and a potential uptake of hormones via the cerebrospinal fluid (CSF) were assessed by lumbar puncture postexercise and at rest (n= 6).

Serotonergic involvement in stress-induced vasopressin and oxytocin secretion.

Objective: To investigate the involvement of serotonin (5-hydroxytryptamine - 5-HT) receptors in mediation of stress-induced arginine vasopressin (AVP) and oxytocin (OT) secretion in male rats.

Design: Experiments on laboratory rats with control groups.

Methods: Different stress paradigms were applied after pretreatment with intracerebroventricular infusion of saline or different 5-HT antagonists.

Effects of sodium intake on cardiovascular variables in humans during posture changes and ambulatory conditions.

The hypothesis was tested that cardiac output (CO) and stroke volume (SV) are increased by a moderate physiological elevation in sodium intake with a more pronounced effect in the ambulatory upright seated than supine position. Fourteen healthy males were investigated during ambulatory and controlled laboratory conditions at the end of two consecutive 5-day periods with sodium intakes of 70 (low) and 250 (high) mmol/24 h or vice versa, respectively. Comparing high and low sodium intake, plasma volume and plasma protein concentrations were 9 and 8% higher in the seated and the supine position, respectively.

Angiotensin II attenuates the natriuresis of water immersion in humans.

The hypothesis was tested that suppression of generation of ANG II is one of the mechanisms of the water immersion (WI)-induced natriuresis in humans. In one protocol, eight healthy young males were subjected to 3 h of 1) WI (WI + placebo), 2) WI combined with ANG II infusion of 0.5 ng.

Effects of supine, prone, and lateral positions on cardiovascular and renal variables in humans.

The hypothesis was tested that changing the direction of the transverse gravitational stress in horizontal humans modulates cardiovascular and renal variables. On different study days, 14 healthy males were placed for 6 h in either the horizontal supine or prone position following 3 h of being supine. Eight of the subjects were in addition investigated in the horizontal left lateral position.