TY - JOUR
T1 - Effect of perfusion rate of cholinergic agonist on sinus node automaticity
AU - Loeb, Jerod M.
AU - deTarnowsky, John M.
AU - Aksamit, Timothy R.
N1 - Funding Information:
The relationship between sinus node artery perfusion and heart rate appear to be rather complex.'. 2. 3. 4 James and Nadeau were the first to report that direct injectidns into the sinus node artery of the in situ canine heart result in the production of injection bradycardia. 5, 6 Hashimoto reported that an inverse correlation existed between sinus node perfusion pressure and heart rate in the cross-perfused dog heart. 1 More recently, Musgrave has documented a bimodal relationship between sinus node artery pressure and sinus depolarization rate in the isolated perfused canine From the Departments of Surgerya nd Physiology,N orthwestern University Medical School. This work was supported in part by National Heart, Lung and Blood Institute Grant R01-HL-29000. The costs of publication of this article were defrayedi n part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. w solely to indicate this fact. Reprint requests to: Dr. Jerod M. Loeb,D epartments of Surgery and Physiology,N orthwestern University Medical School, 303 East Chicago Avenue, Chicago, Illinois 60611.
PY - 1985
Y1 - 1985
N2 - Recent evidence supports a complex relationship between pressure in the sinus node artery and heart rate. In addition, it has been suggested that acetylcholine effects vary depending upon the pressure at which the drug is injected. We examined the cardiac chronotropic responses to acetylcholine, delivered via the sinus node artery using a constant flow perfusion technique. Dogs were anesthetized with chloralose and prepared to record ECG, arterial pressure and bipolar electrograms from the sinus node, sulcus terminalis, right atrium, right ventricle and His bundle. The sinus node artery was catheterized, distribution verified and autologously perfused via the femoral artery. Both vagi and both stellate ganglia were transected. Analog data were processed by computer for each cycle length during perfusion with normal Tyrode solution or Tyrode solution containing acetylcholine. Perfusion of normal Tyrode solution (1-4 ml/min) resulted in prolongation in cycle length which was greater at higher flow rates but rapidly dissipated at all flow rates. Beyond mechanically-induced bradycardia, acetylcholine initially prolonged cycle length but cycle length prolongation faded with time. Delivery of acetylcholine at higher flow rates resulted in significantly greater prolongation of cycle length. Cycle length always returned back toward control although perfusion of acetylcholine continued. Thus, responses to acetylcholine are influenced not only by drug concentration but also by the flow rate at which the drug is delivered. This suggests a coupling of mechanical and pharmacologic components of chronotropic influences at the sinus node.
AB - Recent evidence supports a complex relationship between pressure in the sinus node artery and heart rate. In addition, it has been suggested that acetylcholine effects vary depending upon the pressure at which the drug is injected. We examined the cardiac chronotropic responses to acetylcholine, delivered via the sinus node artery using a constant flow perfusion technique. Dogs were anesthetized with chloralose and prepared to record ECG, arterial pressure and bipolar electrograms from the sinus node, sulcus terminalis, right atrium, right ventricle and His bundle. The sinus node artery was catheterized, distribution verified and autologously perfused via the femoral artery. Both vagi and both stellate ganglia were transected. Analog data were processed by computer for each cycle length during perfusion with normal Tyrode solution or Tyrode solution containing acetylcholine. Perfusion of normal Tyrode solution (1-4 ml/min) resulted in prolongation in cycle length which was greater at higher flow rates but rapidly dissipated at all flow rates. Beyond mechanically-induced bradycardia, acetylcholine initially prolonged cycle length but cycle length prolongation faded with time. Delivery of acetylcholine at higher flow rates resulted in significantly greater prolongation of cycle length. Cycle length always returned back toward control although perfusion of acetylcholine continued. Thus, responses to acetylcholine are influenced not only by drug concentration but also by the flow rate at which the drug is delivered. This suggests a coupling of mechanical and pharmacologic components of chronotropic influences at the sinus node.
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U2 - 10.1016/S0022-0736(85)80053-4
DO - 10.1016/S0022-0736(85)80053-4
M3 - Article
C2 - 4031732
AN - SCOPUS:0022412654
VL - 18
SP - 287
EP - 294
JO - Journal of Electrocardiology
JF - Journal of Electrocardiology
SN - 0022-0736
IS - 3
ER -