Chapter

Arterial Chemoreceptors in Physiology and Pathophysiology

Volume 860 of the series Advances in Experimental Medicine and Biology pp 133-137

Adenosine Receptor Blockade by Caffeine Inhibits Carotid Sinus Nerve Chemosensory Activity in Chronic Intermittent Hypoxic Animals

  • J. F. SacramentoAffiliated withCEDOC, Centro de Estudos Doenças Crónicas, Nova Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa
  • , C. GonzalezAffiliated withDepartamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid, Facultad de Medicina, Instituto de Biología y Genética Molecular, CSIC. Ciber de Enfermedades Respiratorias, CIBERES, Instituto de Salud Carlos III
  • , M. C. Gonzalez-MartinAffiliated withDepartamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid, Facultad de Medicina, Instituto de Biología y Genética Molecular, CSIC. Ciber de Enfermedades Respiratorias, CIBERES, Instituto de Salud Carlos III
  • , S. V. CondeAffiliated withCEDOC, Centro de Estudos Doenças Crónicas, Nova Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa Email author 

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Abstract

Adenosine is a key excitatory neurotransmitter at the synapse between O2-sensing chemoreceptor cells-carotid sinus nerve (CSN) endings in the carotid body (CB). Herein, we have investigated the significance of adenosine, through the blockade of its receptors with caffeine, on the CB hypoxic sensitization induced by chronic intermittent hypoxia (CIH) in the rat. CIH animals were obtained by submitting rats during 15 days from 8:00 to 16:00 to 10 %O2 for 40 s and 20 % O2 for 80 s (i.e., 30 episodes/h). Caffeine (1 mM) was tested in spontaneous and 5 %O2 evoked-CSN chemosensory activity in normoxic and CIH animals. CIH decreased basal spontaneous activity but increased significantly CSN activity evoked by acute hypoxia. Caffeine did not modify basal spontaneous activity in normoxic rats, but decreased significantly by 47.83 % basal activity in CIH animals. In addition, acute application of caffeine decreased 49.31 % and 56.01 % the acute hypoxic response in normoxic and CIH animals, respectively. We demonstrate that adenosine contributes to fix CSN basal activity during CIH, being also involved in hypoxic CB chemotransduction. It is concluded that adenosine participates in CB sensitization during CIH.

Keywords

Chronic intermittent hypoxia Hypoxic sensitization Adenosine Carotid sinus nerve activity Caffeine