Abstract
Sex hormones influence regulation of blood pressure (BP), metabolism and ventilation. In this study we examined whether chronic hyperandrogenemia, characteristic of polycystic ovary syndrome, alters BP, metabolism and ventilatory responses to hypercapnia in female spontaneously hypertensive rats (SHRs). Female SHRs at 4 weeks of age were implanted subcutaneously with dihydrotestosterone pellets (DHT, 7.5 mg/90 days, n=5). Female untreated SHRs were used as control (n=5). At 15 weeks of age, the rats were implanted with telemetry probes to measure BP and heart rate (HR). After 10 days of recovery from surgery, tidal volume (V T ), respiratory frequency (f R ) and pulmonary ventilation (V E ) were measured by whole-body plethysmography during normocapnia (21% O 2 ) or hypercapnia ( 7% CO 2 ). Baseline mean arterial pressure (MAP), heart rate (HR) and body composition were measured. Compared to untreated controls, DHT treated SHRs were heavier (246±3 vs. 201±5g), with more adiposity (23±2 vs. 4±3 g) and lean mass (206±8 vs. 174±9 g), but similar food intake (15±1 vs. 13±1 g) and MAP (141±2 vs. 142±6 mmHg), whereas HR was significantly lower (332±9 vs. 365±6 bpm). The DHT-treated group also showed increased ventilatory response to hypercania (1541 ±161 vs. 1091 ±142 ml.min -1 .kg -1 ), due to increased f R (146±5 vs. 133 breaths/min) and V T (11±1 vs 8±1 ml/kg). MAP and HR responses to hypercapnia were similar between groups. These results indicate that testosterone increases body weight and ventilatory responses to hypercapnia without changing BP in female SHRs. (NHLBI-PO1HL51971, NIGMS-P20GM104357 and AHA SDG5680016)
Published Version
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