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ANP, BNP, and CNP enhance bradycardic responses to cardiopulmonary chemoreceptor activation in conscious sheep

2001; American Physiological Society; Volume: 280; Issue: 1 Linguagem: Inglês

10.1152/ajpregu.2001.280.1.r282

1522-1490

Colleen J. Thomas, Clive N. May, Atul D. Sharma, Robyn L. Woods,

Non-Invasive Vital Sign Monitoring

We demonstrated previously that atrial natriuretic peptide (ANP) enhances reflex bradycardia to intravenous serotonin [5-hydroxytryptamine (5-HT)] (von Bezold-Jarisch reflex) in rats. To determine whether 1) ANP affects this cardiopulmonary vagal reflex in another species and 2) B-type (BNP) and C-type (CNP) natriuretic peptides share with ANP the ability to modulate this reflex, we used intravenous phenylbiguanide (PBG), a 5-HT 3 agonist, as the stimulus to evoke a von Bezold-Jarisch reflex (dose-related, reproducible bradycardia) in conscious adult sheep ( n = 5). Three doses of PBG (13 ± 3, 20 ± 3, and 31 ± 4 μg/kg) injected into the jugular vein caused reflex cardiac slowing of −7 ± 1, −15 ± 2, and −36 ± 3 beats/min, respectively, under control conditions. These doses of PBG were repeated during infusions of ANP, BNP, or CNP (10 pmol · kg −1 · min −1 iv), or vehicle (normal saline). Each of the natriuretic peptides significantly ( P < 0.05) enhanced the sensitivity of bradycardic responses to PBG by 94 ± 8% (ANP), 142 ± 55% (BNP), and 61 ± 16% (CNP). Thus not only did ANP sensitize cardiopulmonary chemoreceptor activation in a species with resting heart rate close to that in humans, but BNP and CNP also enhanced von Bezold-Jarisch reflex activity in conscious sheep.