A model of cardiac nociception in chronically instrumented rats: behavioral and electrophysiological effects of pericardial administration of algogenic substances

摘要: Abstract This report presents evidence that pericardial administration of a mixture algogenic substances is potentially useful model cardiac nociception. In awake rats in which looped silicone catheter had been placed the sac at least 5 days previous, containing equal concentrations bradykinin (BK), acetylcholine (ACh), adenosine (ADEN), histamine (HIST), serotonin (5-HT) and prostaglandin E2 (PGE2) (total 25 nmol μl) led to rapid acquisition passive avoidance behavior. contrast, neither BK alone (5–25 nmol) nor same ACh, ADEN, HIST, 5-HT PGE2without behavior or produced effects significantly different than by saline given into volume (25 μl). Both dose-dependent cardiovascular responses (pressor response tachycardia) similar magnitude. Neither without significant changes mean arterial blood pressure heart rate.In electrophysiological experiments rats, thoracic spinal cord neurons responded dose-dependently and, except for one neuron, also manner. However, BK, when compared dosage contained mixture, were less magnitude duration. All units received convergent somatic input from thorax all esophagus. Balloon distension esophagus excited units.Results behavioral characterization administered gave differences between six substances, including BK. either two dosages tested not while was aversive. complementary studies, both neurons, suggesting neuron putative are necessarily reliable measures