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Gestational administration of glucocorticoid alters baroreceptor and chemoreceptor reflexes in rat
Author(s) -
Polson Jaimie William,
Paton Julian FR,
Wolf Andrew R
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.738.17
Subject(s) - baroreflex , medicine , baroreceptor , heart rate , endocrinology , bradycardia , chemoreceptor , reflex , glucocorticoid , reflex bradycardia , blood pressure , dexamethasone , mean arterial pressure , anesthesia , receptor
In the rat, administration of high levels of glucocorticoid during pregnancy produces late onset hypertension in the offspring. The causes of hypertension are not known, but may involve alterations in cardiovascular autonomic control. We examined baro‐ and chemoreflex changes in heart rate (HR) and sympathetic nerve activity (SNA) in the rat following gestational dexamethasone administration (DEX), using the in situ working heart brainstem preparation. Pregnant dams were administered DEX (200 μg/kg s.c.) at E15–16. At 3–5 weeks, perfusion pressure, HR, and activity of the phrenic nerve and thoracic sympathetic chain were measured in the in situ preparation of DEX offspring and naive controls. HR and SNA responses to baroreceptor (increase in pressure of 20–30 mmHg) and chemoreceptor (injection of 20–100 μL 0.03% NaCN) stimulation were measured. Baroreflex changes in HR gain (control, 1.3+0.2 v 0.8+0.2 bpm/mmHg) and SNA (16+4 v 6+1 %baseline/mmHg) were lower in the DEX rat than control (P<0.05, n=4), whereas the chemoreflex responses were augmented (bradycardia of 161+30 v 217+15 bpm and sympathoexcitation of 60+14 v 106+13 %baseline, P<0.05, n=4). The results indicate that cardiovascular autonomic reflexes are altered in the DEX hypertension in such a way as to facilitate an increase in sympathetic drive. This may contribute to the ontogeny of hypertension in this model. Support: British Heart Foundation