Hypoxia-induced changes in parasympathetic neurochemical markers in guinea pig heart

Authors:
  • LCL. H. Crockatt
    L. H. Crockatt
  • DLD. D. Lund
    D. D. Lund
  • PSP. G. Schmid
    P. G. Schmid
  • RRR. Roskoski
    R. Roskoski
  • FLFabiola León-Velarde
    Fabiola León-Velarde
  • JRJean-Paul Richalet
    Jean-Paul Richalet
  • JCJuan-Carlos Chavez
    Juan-Carlos Chavez
  • RKRachid Kacimi
    Rachid Kacimi
  • MRMaria Rivera-Chira
    Maria Rivera-Chira
  • JPJosé-Antonio Palacios
    José-Antonio Palacios
  • DCDaniel Clark
    Daniel Clark
  • WSW. I. Sivitz
    W. I. Sivitz
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Abstract
Exposure of animals to hypoxia produces cardiovascular changes including right ventricular hypertrophy and alterations in heart rate. The activity of choline acetyltransferase, a neurochemical marker of parasympathetic innervation, and the density of muscarinic cholinergic receptors, measured by the binding of [3H]quinuclidinyl benzilate, were analyzed in the hearts of guinea pigs exposed to hypobaric hypoxia. We found a significant increase in the activity of choline acetyltransferase in the sinoatrial node in response to hypoxia after 7 or 14 days. In addition, we found significant decreases in the muscarinic receptor density in several contractile and conducting regions. The decrease in receptor density may reflect regulation by the level of occupancy; an increased occupancy may produce a decrease in muscarinic receptor number.