Biomedical subjects

J R Claybaugh

Publications and source records attributed to J R Claybaugh.

68 records · Page 4Linked to original sources

PubMed1980

Plasma renin activity, vasopressin concentration, and urinary excretory responses to exercise in men.

Plasma vasopressin concentration (PAVP), renal function, and effectors of vasopressin release were evaluated in male volunteers during running at heart rates of 0, 35, 70, and 100% of maximum after 10 h abstinence from water (normal hydration) and at 100% after ingestion of 300 ml water. Plasma renin activity (PRA) and PAVP were linearly correlated and correlated to work intensity over all observations. Changes in PAVP were not correlated with changes in plasma osmolality (POSMOL) and plasma volume (PV) over all observations. Furthermore, despite similar changes in POSMOL, PV, PRA, body weight, mean arterial pressure, and plasma lactate concentration, the increase in PAVP after maximal exercise was greater during normal hydration than the water-supplemented state. Decreased urine flow observed in association with exercise was characterized by increased free water and decreased osmotic and creatinine clearances. Thus increased PAVP associated with exercise appears not to play a role in the concomitant antidiuresis. Vasopressin stimuli are probably variable at different times during exercise and may include factors other than those measured.

Adult↗

PubMed1979

Urinary excretion of water and electrolytes during open-sea saturation diving to 850 fsw.

The dive was carried out in the open sea to a depth of 850 fsw (26.7 ATA) for 6 days (DD 1--6) in the saturated mode, with personnel transfer capsule (PTC) excursions between 0 and 150 fsw and diver excursions between 0 and 50 fsw from the saturation base. Each diver had two excursion dives on alternate days. Although each PTC excursion lasted approximately 7 h, the actual time spent in the water averaged 10.5 min per diver. For 12 divers, daily excretion of water, electrolytes, aldosterone, and antidiuretic hormone (ADH) was studied, along with plasma composition (including prolactin), before, during, and after hyperbaric exposure. A significant increase in urine flow was observed on DD2--4 (1604 ml/day predive vs. 2300 ml/day on DD 4; P less than 0.05), after which the degree of diuresis decreased to about 1800 ml/day. Urine osmolality changed inversely with urine flow, with the lowest value of 532 mOsm/kg on DD 4. During the postdive period, both urine flow and urine osmolality returned to the predive level. The endogenous creatinine clearance was maintained at about 200 liters/day throughout the dive. The fractional excretion of Na+ remained unchanged while that of K+ increased significantly during hyperbaric exposure, thus decreasing the urinary Na+/K+ ratio. The fractional excretion of total osmotic substances showed a small hyperbaric exposure. Body weight decreased progressively during the initial 4 days of pressure exposure, equalling 2.6 kg on DD 4. These findings suggest that the observed diuresis may be accompanied by a net loss of body water. Neither the plasma prolactin level nor urinary excretion of aldosterone and ADHshowed any consistent change throughout the dive. It thus appears that, although there is a small osmotic component, the observed diuresis is primarily due to the ADH-independent inhibition of fre water reabsorption from the collecting duct by means of a mechanism yet to be identified.

Adult↗

PubMed1978

Response of antidiuretic hormone to acute exposure to mild and severe hypoxia in man.

Eight men, 19-35 years of age, breathed 20.9% (normal oxygen), 13.9% (mild hypoxia) or 11.1% (severe hypoxia) oxygen in nitrogen gas mixtures during three 20 min periods, which were separated by 1 h recovery periods. The order in which the gas mixtures were breathed was random. The partial pressure of oxygen decreased from a mean of 93.5 during exposure to normal oxygen to 53.9 and 36.7 mmHg during mild and severe hypoxia respectively. There were corresponding decreases in haemoglobin saturation. The partial pressure of carbon dioxide was lower and the pH higher during severe hypoxia than during exposure to normal oxygen. There were no changes in the plasma osmolality or in the concentrations of sodium or potassium in the plasma. There was a tendency for both the renin activity and the concentration of aldosterone in the plasma to decrease progressively as the percentage of oxygen breathed decreased. Unlike severe hypoxia, mild hypoxia suppressed the concentration of antidiuretic hormone (ADH) in the plasma of all subjects by about 59%; during severe hypoxia the reduction was not significant, being only about 33%. These data are consistent with the suggestion that the effect of hypoxia on the release of ADH is dependent on the level of hypoxia.

Adult↗

PubMed1977

Hana kai ii: a 17-day dry saturation dive at 18.6 ATA. III. Body fluid balance.

Comprehensive studies on body fluid balance on 5 divers were conducted during the Hana Kai II dive (17 days at 18.6 ATA and 7 days of decompression). Daily urine flow increased from about 2000 ml at 1 ATA to 2600 ml at 18.6 ATA, at 31 degrees C. This diuresis was accompanied by a reduction in urine osmolality (from 650 to 500 mOsm) and a slight increase in osmolal clearance. Endogenous creatinine clearance remained at about 173 ml/min throughout the dive. Despite such a sustained diuresis, neither daily water intake nor total body water volume changed significantly. The plasma renin activity changed little, while both plasma aldosterone concentration and urinary aldosterone excretion increased significantly during the first week at 18.6 ATA. The plasma prolactin concentration showed a significant decrease during the first 3 days at 18.6 ATA. The daily excretion of antidiuretic hormone (ADH) decreased significantly (by 40%) 4 days after compression and remained low throughout the rest of the dive. Insensible waterloss at 18.6 ATA was 35% lower than that at 1 ATA. It is suggested that the observed hyperbaric diuresis is due primarily to suppression of ADH as a result of suppression of insensible water loss.

Aldosterone↗

PubMed1975

Ethanol-induced lowering of arterial oxyhemoglobin saturation during hypoxia.

Nine fasting, healthy, adult male volunteers were given oral carbohydrate before exposures to normoxia (PIO2 = 149 torr) and mild hypoxia (PIO2 = 98 torr). Following recovery, they were given oral ethanol before similar exposure to normoxia and mild hypoxia. Repeated measures of arterial blood and expired gases were made. Ethanol diminished respiratory gas exchange (R), causing lower alveolar and arterial oxygen pressures during normoxia and mild hypoxia and a reduction in arterial oxygen saturation from 89.9 to 87.4% during mild hypoxia. It is suggested that carbohydrates are preferable to ethanol and fats as nutrients during limited oxygen transport situations, such as high-altitude, carbon monoxide exposure, or during heavy exertion, and for patients with cardiovascular or pulmonary disease.

Administration, Oral↗

PubMed1975