Pregnancy alters baroreflex gain and range, but the mechanism of this change is not known. To determine if pregnancy alters the cardiac response to autonomie receptor stimulation we studied isolated buffer-perfused hearts from virgin (NP) and pregnant (P, 28 day gestation) rabbits, β-Adrenergic and cholinergic receptors were activated with isoproterenol (ISO, 0.3-300 nM) or acetylcholine (ACh, 0.310,000 μM). Drugs were infused in half-log increments and given in random order Hearts receiving ISO had cholinergic blockade with atropine (5 μM), and hearts receiving ACh had βadrenergic blockade with propranolol (1 nM). All hearts had aadrenergic blockade with phenoxybenzamine (10 nM). ISO caused a dose-dependent increase in heart rate; this relationship was shifted leftward 1 log order in P hearts as compared to NP hearts. Conversely, ACh caused a dosedependent decrease in heart rate; this relationship was shifted rightward Vi log order in P hearts as compared NP hearts. We conclude that pregnancy augments the cardiac response to β-adrenergic receptor activation and diminishes the cardiac response to cholinergic receptor activation.
|Original language||English (US)|
|State||Published - Dec 1 1996|
ASJC Scopus subject areas
- Molecular Biology