Effect of increases in myocardial epinephrine content on epinephrine release from the dog heart.
The effect of short-term (10 min) and prolonged (180 min) epinephrine (E) infusion (92.5 ng.kg-1.min-1) on E content of the myocardium and on the subsequent release of E from the heart during stimulation of the left stellate ganglion (4 and 10 Hz, 4 V, 2 ms, 1 min) was studied in anesthetized dogs. The E content in the free wall of the left ventricle significantly increased 1.7- and 4.2-fold following short-term and prolonged E infusion, respectively, compared with a control group infused with saline. Tissue norepinephrine (NE) content was not modified by E infusion. The plasma E concentration gradient across the heart indicated a significant release of E during electrical stimulation of the left stellate ganglion, which was related to the amount of E stored in the tissue (e.g., control, 126 +/- 60; 10-min infusion, 279 +/- 105; 180-min infusion, 1487 +/- 287 pg.mL-1; at 10 Hz). NE release from the heart also tended to increase with the amount of E stored in the myocardium and released upon electrical stimulation of the left stellate ganglion, although the difference did not reach statistical significance. These results provide further direct evidence that blood-borne E can be taken up and stored in sympathetic nerve endings and can be released as a cotransmitter with NE. Locally released E could favor NE release.
Péronnet
F
F
Département d'éducation physique, Université de Montréal, QC, Canada.
Boudreau
G
G
de Champlain
J
J
Nadeau
R A
RA
D000758:Anesthesia; D000818:Animals; D001011:Aorta / Q000378:metabolism; D001794:Blood Pressure / Q000187:drug effects; D002395:Catecholamines / Q000097:blood / Q000378:metabolism; D004285:Dogs; D004558:Electric Stimulation; D004837:Epinephrine / Q000008:administration & dosage / Q000378:metabolism* / Q000494:pharmacology; D006321:Heart / Q000187:drug effects / Q000294:innervation; D006339:Heart Rate / Q000187:drug effects; D007262:Infusions, Intravenous; D009206:Myocardium / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism; D013233:Stellate Ganglion / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology; D016277:Ventricular Function, Left / Q000187:drug effects
D002395:Catecholamines; D009638:Norepinephrine; D004837:Epinephrine