Cardiovascular and endocrine responses to 90 degree tilt during a 35-day saturation dive to 46 and 37 ATA.

Introduction: Hyperbaria-induced diuresis is accompanied by decreased basal and stimulated release of arginine vasopressin (AVP) and decreased blood volume possibly contributing to the reported orthostatic intolerance. Since hyperosmolality is not a consistent finding, the explanation of blood volume reduction at hyperbaria must involve an osmotic component to the diuresis. Investigations of a possible involvement of atrial natriuretic peptide (ANP) to the hyperbaric diuresis have revealed mixed results.

Gender differences in the blood volume of conscious Sprague-Dawley rats.

Reference values of blood volume (BV) and plasma volume (PV) of animal species are given as functions of body weight and gender specification generally is not given. Considering the common observation of a decreased hematocrit (Hct) in the females of many species, the BV, the PV, or both must differ between genders. The present study was performed to determine the magnitude of those differences.

Effects of prenatal ethanol exposure and sex on the arginine vasopressin response to hemorrhage in the rat.

AVP synthesis, storage, and osmotically stimulated release are reduced in young adult rats exposed prenatally to ethanol (PE). Whether the reduced release of AVP to the osmotic stimulus is due to impairment of the vasopressin system or specifically to an osmoreceptor-mediated release is not known. The present experiments were done, therefore, to determine whether a hemorrhage-induced AVP response would also be diminished in PE-exposed rats.

The effects of residency on physical fitness among military physicians.

Purpose: Demands of medical residency training would be expected to result in physical deconditioning. This study determined the effects of residency on physical fitness.

Methods: A prospective cohort study of the change in physical conditioning during residency using the Army Physical Fitness Test as a standardized measure of fitness was conducted.

Prenatal exposure to ethanol causes partial diabetes insipidus in adult rats.

Chronic consumption of ethanol in adult rats and humans leads to reduced AVP-producing neurons, and prenatal ethanol (PE) exposure has been reported to cause changes in the morphology of AVP-producing cells in the suprachiasmatic nucleus of young rats. The present studies further characterize the effects of PE exposure on AVP in the young adult rat, its hypothalamic synthesis, pituitary storage, and osmotically stimulated release. Pregnant rats were fed a liquid diet with 35% of the calories from ethanol or a control liquid diet for days 7-22 of pregnancy.

Attitudes and knowledge about continuous oral contraceptive pill use in military women.

Objective: The goal of this study was to determine attitudes toward oral contraceptive pill (OCP)-induced amenorrhea among U.S. Army women.

Effects of FiO2 on O2 consumption and cardiovascular and hormonal responses to hemorrhage in the goat.

This study was conducted to determine whether 100% FiO2 during hemorrhage would improve maintenance of mean arterial blood pressure and to assess the cardiovascular, arginine vasopressin, and renin-angiotensin system roles in the response. This also allowed evaluation of FiO2 effects on the baroreceptor control of these hormone systems. Six conscious female goats were hemorrhaged (0.

Effects of time of day, gender, and menstrual cycle phase on the human response to a water load.

Estrogen and progesterone interference with renal actions of arginine vasopressin (AVP) has been shown. Thus we hypothesized that women will have a higher water turnover than men and that the greatest difference will be during the luteal phase of the menstrual cycle. Seven men (32 +/- 3 yr) and six women (33 +/- 2 yr) drank 12 ml water/kg lean body mass on different days at 0800 and at 2000 following 10 h of fast and a standardized meal at 0600 and 1800.

Renal, endocrine, and cardiovascular responses during head-out water immersion in legless men.

Background: The hydrostatic pressure gradient during head-out water immersion (HOI) causes a blood shift from the legs into the thoracic cavity to stretch the receptors in the cardiac atria and results in a diuresis in hydrated subjects. The present study was conducted to examine whether the HOI-induced diuresis and related circulatory and hormonal changes were attenuated in the subjects who had no legs (legless men).

Methods: Two legless men served as the subjects.

Prospective randomized double blind placebo-controlled evaluation of azithromycin for treatment of cat-scratch disease.

Objective: To determine the efficacy of azithromycin in the treatment of patients with typical cat-scratch disease.

Design: Prospective, randomized, double blind, placebo-controlled clinical trial.

Setting: Large military medical center and its referring clinics.

Renal function in hyperbaric environment.

During mixed gas saturation diving (to 3-49.5 ATA) daily urine flow increases by about 500 ml/day, with no changes in fluid intake and glomerular filtration rate. The diuresis is accompanied by a significant decrease in urine osmolality and increase in excretion of such solutes as urea, K+, Na+, Ca2+ and inorganic phosphate (Pi).

Renal and hormonal responses to exercise in man at 46 and 37 atmospheres absolute pressure.

Background: Exercise increases plasma arginine-vasopressin (PAVP), plasma atrial natriuretic peptide (PANP), plasma renin activity (PRA), and plasma aldosterone (PALDO) in an intensity-dependent manner. With acute exercise, urine osmolality (UOSM) is often decreased despite increased PAVP. The hyperbaric environment lowers PAVP and UOSM, and increases urine flow.

Furosemide-induced airway relaxation in guinea pigs: relation to Na-K-2Cl cotransporter function.

This study tested the hypothesis that airway relaxation to furosemide is mediated via the Na-K-2Cl cotransporter. If this mechanism exists in airway smooth muscle like in vascular smooth muscle, changes in airway relaxation should be associated with changes in Na-K-2Cl cotransporter function, and both should be substrate dependent. Tracheal rings from newborn guinea pigs were bathed in standard (STD) or varying low Cl- concentration ([Cl-]) N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES).

Mechanism for changes in vasopressin during acute exposure at 3 atm abs air.

Plasma arginine vasopressin (AVP) concentration is reduced in human subjects during prolonged saturation dive exposures of 4 atmospheres absolute (atm abs) and greater. The objectives of the present study were to determine if AVP would be reduced in eight male subjects during a 1-h exposure of 3 atm abs air and, if so, to determine the mechanisms responsible for the AVP response. Assessments of transmural central venous pressure (central venous pressure-esophageal pressure) and cardiac volume measurements were made to evaluate the possible role of cardiopulmonary receptors on the AVP response.

Diurnal renal responses in man to water loading at sea level and 31 atm abs.

The hyperbaric environment causes a sustained diuresis accompanied by normal water intake and a decrease in insensible water loss. The maintained water intake may be necessary for the maintenance of water balance because of a reduced ability of the kidney to retain water, or may be causal in the diuresis. This problem was studied in four male subjects.

Changes in muscle sympathetic nerve activity and renal function during positive-pressure breathing in humans.

The possibility that the decreased urinary flow during continuous positive-pressure breathing (CPPB) may be a consequence of a reflex mediated via the cardiopulmonary baroreceptors to increase neurohumoral secretion or to change the sympathetic outflow was assessed. Muscle sympathetic nerve activity (MSNA) on the right peroneal nerve, vasoactive hormones, and renal and cardiovascular responses were measured during CPPB (+12 mmHg) in 10 male subjects (22.0 +/- 0.

Technique for placement of chronic third cerebroventricular cannula in female goats (Capra hircus).

A practical method for chronic catheterization of the third cerebroventricular space in goats was developed by using a stereotaxic device. In female goats of various ages and weights, a stereotaxically mounted drill was positioned at an angle of 11.5 degrees with the tip of the drill bit located at a skull reference point 2 to 3 mm rostral to the posterior border of Bregma (intersection of the coronal with the sagittal sutures).

Metabolism of neurohypophysial hormones.

Over the past decade several new routes of neurohypophysial hormone metabolism have been identified. These include nonhepatic splanchnic clearance and renal clearance in addition to filtration that appears to be receptor mediated. The intraluminal degradation of VP in the proximal tubule, and distal tubular secretion, at least in one species, has been identified.

Hypoxia attenuates the renin response to hemorrhage.

We studied hypoxia and hypotensive hemorrhage in conscious female goats. After control, goats continued an experimental period in normoxia or hypoxia [fractional inspired oxygen concentration (FIO2) = 0.10] for 120 min.

Renal responses during a dry saturation dive to 450 msw.

Four subjects were compressed to a simulated depth of 450 msw (46 bar) for 37 days in the main research chamber of the German underwater simulator diving facility at the GKSS Research Center, Geesthacht. The ambient gas was trimix. Urine was collected at 0700, 1300, and 1900 h each day for analysis of Na+, K+, volume, osmolality, and creatinine.

Urinary vasopressin and aldosterone and plasma volume during a saturation dive to 450 m.

Urinary vasopressin (VP), aldosterone (ALDO), osmotic substances, sodium excretion, and plasma volume were assessed in 4 healthy male divers during 2 predive control days, 2 compression days, 6 days at 46 atm abs, and 26 days of decompression with stops at 37 and 27 atm abs. At pressure the ambient gas was trimix (0.5 atm abs O2:5% N2:remainder He).

Comparative effects of Des Leu Angiotensin I and Angiotensin II on AVP secretion from the hypothalamoneurohypophysis and pituitary of the rat.

In the present study we compared the effects of Des Leu Angiotensin I (Des Leu AI) with Angiotensin II (AII) on the secretion of vasopressin (AVP) from the isolated hypothalamoneurohypophyseal system (HNS) and isolated posterior pituitary gland of the rat. Administration of 10(-6)M, 10(-5) M and 10(-4) M Des Leu AI was without significant effect on AVP secretion from the HNS. A similar phenomenon was seen in the posterior pituitary with 10(-6) M and 10(-5) M Des Leu AI, although 10(-4) M significantly increased AVP release.