Low urinary 6-sulfatoxymelatonin levels in patients with severe congestive heart failure.

Objective: To assess urinary 6-sulfatoxymelatonin excretion in patients admitted to the hospital because of congestive heart failure (CHF).

Methods: Urinary 6-sulfatoxymelatonin was measured by a specific radioimmunoassay in 33 hospitalized patients with CHF and in 146 healthy ambulatory volunteers. Individuals with hepatic or renal failure were excluded from the sample.

In vitro effect of melatonin on oxygen consumption in liver mitochondria of rats.

Objective: To examine the in vitro effect of melatonin on rat mitochondrial liver respiration.

Methods: Oxygen consumption by liver mitochondria was measured polarographically in the presence of one of the following Krebs' cycle substrates: Lsuccinate, DL-3- beta-hydroxybutyrate or L-malate. Respiratory velocities at rest (state 4) and during rapid respiration in the presence of substrate and adenosine diphosphate (state 3) were measured in the presence of 10 (-9)-10(-3) M concentrations of melatonin.

Melatonin increases oestradiol-induced bone formation in ovariectomized rats.

To assess the effect of melatonin on bone metabolism in ovariectomized rats, receiving oestradiol therapy or not, melatonin was administered in the drinking water (25 microg/mL water) and oestradiol (10 microg/kg body weight) or vehicle was given subcutaneously 5 days/week for up to 60 days after surgery. Urinary deoxypyridinoline (a marker of bone resorption) and circulating levels of bone alkaline phosphatase activity (a marker of bone formation), as well as serum calcium and phosphorus levels, were measured every 15 days. Bone area (BA), bone mineral content (BMC), bone mineral density (BMD) and total body fat (expressed as 100 g body weight) were measured by dual-energy X-ray absorptiometry at the end of the experiment.

Vascular reactivity in diabetic rats: effect of melatonin.

The aim of the present study was to evaluate the in vitro contractile response of rat aorta in mild and severe type I diabetes and the effect of melatonin on it. Aortic rings were obtained from male Wistar rats injected with streptozotocin 8-12 wks earlier. Rats were divided into three groups: non-diabetic rats (NDR), mildly diabetic rats (MDR) and severely diabetic rats (SDR).

A multifactorial approach employing melatonin to accelerate resynchronization of sleep-wake cycle after a 12 time-zone westerly transmeridian flight in elite soccer athletes.

Rapid transmeridian translocation through multiple time zones has a negative impact on athletic performance. The aim of the present study was to test the timely use of three factors (melatonin treatment, exposure to light, physical exercise) to hasten the resynchronization of a group of elite sports competitors and their coaches to a westerly transmeridian flight comprising of 12 time-zones. Twenty-two male subjects were included in the study.