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We hypothesized that orthostatic tolerance is higher in young, healthy black compared with white women. To determine orthostatic tolerance, 22 women (11 black and 11 white) underwent graded lower body negative pressure to presyncope. We measured blood pressure, heart rate, and R-R interval (ECG) continuously at baseline and through all of the levels of(More)
To determine if estrogen upregulates osmotic secretion of arginine vasopressin (AVP) and alters body water balance, we infused hypertonic (3% NaCl) saline in 6 women (68 +/- 3 yr) after 14 days of 17 beta-estradiol (transdermal patch, approximately 0.1 mg/day, E2) and placebo (control) administration. Hypertonic saline was infused at 0.1 ml.kg-1.min-1 for(More)
Accurate and early detection of blood volume loss would greatly improve intraoperative and trauma care. This study has attempted to determine early diagnostic and quantitative markers for blood volume loss by analyzing photoplethysmogram (PPG) data from ear, finger and forehead sites with our high-resolution time-frequency spectral (TFS) technique in(More)
To determine the effect of estrogen and progesterone on plasma volume (PV) and extracellular fluid volume (ECFV), we suppressed endogenous estrogen and progesterone by using the gonadotropin-releasing hormone (GnRH) antagonist ganirelix acetate in seven healthy women (22 +/- 1 yr). Subjects were administered GnRH antagonist for 16 days. Beginning on day 5(More)
To test the hypothesis that progesterone, independent of estrogen, decreases the plasma osmotic threshold for arginine vasopressin (AVP) release and thirst onset, we compared AVP and thirst responses to hypertonic saline infusion (HSI) during administration of oral contraceptives (OCs) containing progesterone (OCP) with responses to infusion of OCs(More)
We tested the physiological reliability of plasma renin activity (PRA) and plasma concentrations of arginine vasopressin (P[AVP]), aldosterone (P[ALD]), and atrial natriuretic peptide (P[ANP]) in the early follicular phase and midluteal phases over the course of two menstrual cycles (n = 9 women, ages 25 +/- 1 yr). The reliability (Cronbach's alpha >/=0.80)(More)
Autonomic mechanisms are fundamental to human physiological thermoregulation, and female reproductive hormones have substantial influences on several aspects of these mechanisms. Of these, the best recognized are the thermoregulatory responses that occur at menopause (hot flushes) and the changes in body temperature within the menstrual cycle which may help(More)
Hyperandrogenism and vascular dysfunction often coexist in women with polycystic ovary syndrome (PCOS). We hypothesized that testosterone compromises cutaneous microvascular dilation in women with PCOS via the endothelin-1 ET-B subtype receptor. To control and isolate testosterone's effects on microvascular dilation, we administered a gonadotropin-releasing(More)
Interaction between the autonomic nervous system and the neuroendocrine system is critical for maintenance of homeostasis in a wide variety of physiological parameters such as body temperature, fluid and electrolyte balance, and blood pressure and volume. The anatomical and physiological mechanisms underlying integration of the neuroendocrine and autonomic(More)
Obesity is a metabolic state in which excess fat is accumulated in peripheral tissues, including the white adipose tissue, muscle, and liver. Sustained obesity has profound consequences on one's life, which can span from superficial psychological symptoms to serious co-morbidities that may dramatically diminish both the quality and length of life. Obesity(More)