Development of a method to determine autonomic nervous system function in the rat.
A noninvasive method to evaluate autonomic nervous system (ANS) function in animals is needed for studies of diabetic autonomic neuropathy. These studies modified the RR-variation test, used to test diabetic ANS function in humans, and applied it to rats. Permanent wire electrodes were implanted in the chest wall of a rat. ECG complexes were obtained by connecting the electrodes to leads going to an impedence pneumograph and high gain coupler. This information was then converted into square waves by a trigger unit and recorded on magnetic tape for subsequent analysis by computer. Recordings were at least 60 seconds long, of which 30 seconds was used for analysis. In order to establish autonomic influence, RR-variation was measured before and after application of pharmacologic agents. Directly decreasing parasympathetic tone with atropine (20 mg/kg, n = 6) increased heart rate (P less than 0.001) and decreased RR-variation (P less than 0.05). Directly decreasing beta adrenergic tone with propranolol (10 mg/kg, n = 7) decreased heart rate (P less than 0.01) but had no effect on RR-variation (NS). Stimulation of the beta adrenergic receptors (isoproterenol, 0.1 mg/kg, n = 5) increased heart rate (P less than 0.01) but decreased RR-variation (P less than 0.01). Increasing parasympathetic tone reflexly with alpha-1 adrenergic receptor stimulation (phenylephrine, 1 mg/kg, n = 7) decreased heart rate (P less than 0.05) and increased RR-variation (P less than 0.025). The responses to phenylephrine could be blocked by parasympathetic blockade. Phentolamine (0.1 mg/kg, n = 7) caused an increase in heart rate (P less than 0.001) and a decrease in RR-variation (P less than 0.01). The responses to phentolamine could be blocked by beta adrenergic receptor blockade.(ABSTRACT TRUNCATED AT 250 WORDS)
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000758:Anesthesia; D000818:Animals; D001341:Autonomic Nervous System / Q000502:physiology*; D002940:Circadian Rhythm; D003929:Diabetic Neuropathies / Q000503:physiopathology; D004562:Electrocardiography; D006339:Heart Rate / Q000187:drug effects; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008722:Methods; D010646:Phentolamine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D000317:Adrenergic alpha-Antagonists; D010656:Phenylephrine; D011433:Propranolol; D007545:Isoproterenol; D010646:Phentolamine