[Effect of atropine, propranolol, phentolamine, and orciprenaline on minute-rhythmic fluctuations of heart rate in urethane-anesthetized mice].
The effects of atropine, propranolol, phentolamine, and orciprenaline on the minute-rhythmic fluctuations of the heart rate were investigated in urethane-anaesthetized mice. These drugs influenced the parameters of the minute rhythm (amplitude, length of period). However, the rhythm was not suppressed over any length of time. After blocking the vagus with atropine, the rhythm was maintained unchanged. In the other cases, the rhythm was not demonstrable only during the transition to a new level of heart rate. Immediately after the injection of each drug, the amplitude of the minute rhythm was very low for the most part but gradually increased in size again. After the injection of each drug, there existed the same correlations between the length of period of the fluctuations of heart rate and the respective mean rate (i.e., the arithmetic mean of both extreme values of a period) as after the injection of urethane alone. The same rhythms as are characteristic for the respective ranges of heart rate after the injection of urethane alone were also observed. The possible central and peripheral mechanism of origin of this minute rhythm are discussed. Since neither the blockade of the vagus nor the blockade of the sympathetic innervation could suppress the occurrence of periodic fluctuations of the heart rate for a long time, a peripheral origin of this minute rhythm may be assumed. Moreover, because there are no indications for a direct influence of urethane on the cardiac pacemaker, urethane might be supposed to produce the conditions for a pronounced appearance of the latently existing autogenic rhythm of the heart by acting on the central nervous system. Therefore, the visceral nervous system would be responsible only for the modification of the parameters (amplitude, length of period) of this rhythm.
D000758:Anesthesia; D000818:Animals; D001285:Atropine / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects*; D008297:Male; D009921:Metaproterenol / Q000494:pharmacology*; D051379:Mice; D010646:Phentolamine / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology*; D013997:Time Factors; D014520:Urethane
D014520:Urethane; D009921:Metaproterenol; D001285:Atropine; D011433:Propranolol; D010646:Phentolamine
Der Einfluss von Atropin, Propranolol, Phentolamin und Orciprenalin auf die minutenrhythmischen Schwankungen der Herzfrequenz bei der Maus in der Urethan-Narkose.