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Hypoxia- and normoxia-induced reversibility of autonomic control in Andean guinea pig heart

1996; American Physiological Society; Volume: 81; Issue: 5 Linguagem: Inglês

10.1152/jappl.1996.81.5.2229

8750-7587

Fabiola León‐Velarde, Jean‐Paul Richalet, Juan-Carlos Chavez, Rachid Kacimi, Maria C. Rivera, José-Antonio Palacios, Daniel Clark,

Cardiovascular and exercise physiology

León-Velarde, Fabiola, Jean-Paul Richalet, Juan-Carlos Chavez, Rachid Kacimi, Maria Rivera-Chira, José-Antonio Palacios, and Daniel Clark. Hypoxia- and normoxia-induced reversibility of autonomic control in Andean guinea pig heart. J. Appl. Physiol. 81(5): 2229–2234, 1996.—We herein describe the regulation of cardiac receptors in a typical high-altitude native animal. Heart rate response to isoproterenol (HR Iso ) (beats ⋅ min −1 ⋅ mg Iso ⋅ kg −1 ) and atropine, the density of β-adrenergic (β AR ) and muscarinic (M 2 ) receptors, and the ventricular content of norepinephrine (NE) and dopamine (DA) were studied in guinea pigs ( Cavia porcellus). Animals native to Lima, Peru (150 m) were studied at sea level (SL) and after 5 wk at 4,300-m altitude (SL-HA). Animals native to Rancas [Pasco, Peru (4,300 m)] were studied at high altitude (HA) and after 5 wk at SL (HA-SL). HA animals had a lower HR Iso , maximum number of β AR binding sites (B max ), β AR dissociation constant ( K d ), NE, and DA ( P < 0.05) and a higher M 2 B max ( P < 0.001) when compared with the SL group. HA-SL showed an increase of the HR Iso , β AR K d , and NE ( P < 0.05) and a decrease of the M 2 B max and K d ( P < 0.0001) when compared with the HA group. The present study demonstrates the differential regulation and reversibility of the autonomic control in the guinea pig heart.