Age-related response to epinephrine-induced myocardial stress. A functional and ultrastructural study.
Left ventricular systolic and diastolic function before, during, and after a 2-hour intravenous infusion of epinephrine at either 0.5 micrograms/kg/min or 2 micrograms/kg/min were assessed by pressure-volume data obtained by conductance catheter micromanometer technique and correlated with cardiac ultrastructure and plasma levels of epinephrine in neonatal (3-5 days old, n = 12) versus adult (3-4 months old, n = 11) pigs. Administration of epinephrine at 0.5 micrograms/kg/min resulted in an increase in end-systolic elastance (Ees) only in adults, whereas at 2.0 micrograms/kg/min Ees increased in both groups. After 2-hour administration of epinephrine at 2.0 micrograms/kg/min, Ees decreased significantly (p less than 0.05) from the preinfusion baseline value of 8.9 +/- 2 (mean +/- SD) to 5 +/- 1.7 mm Hg/ml, and a significant (p less than 0.05) increase in left ventricular volume elasticity (VdP/dV) from 0.4 +/- 0.02 to 1.4 +/- 0.2 mm Hg occurred in neonates versus no change from baseline in either Ees or VdP/dV in the adults. These changes in the neonates were associated with sarcolemmal rupture and mitochondrial Ca2+ granule deposition versus normal cardiac ultrastructure in the adults. We conclude that the neonatal myocardium is more susceptible to cardiotoxicity from circulating epinephrine.
Division of Cardiovascular Surgery, Hospital for Sick Children, Toronto, Canada.
J
J
Caspi
J G
JG
Coles
L N
LN
Benson
S L
SL
Herman
R J
RJ
Diaz
J
J
Augustine
A
A
Brezina
A
A
Kolin
G J
GJ
Wilson
D000375:Aging / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D004837:Epinephrine / Q000008:administration & dosage / Q000494:pharmacology*; D008854:Microscopy, Electron; D009200:Myocardial Contraction / Q000187:drug effects* / Q000502:physiology; D009206:Myocardium / Q000648:ultrastructure*; D013552:Swine; D013997:Time Factors; D016277:Ventricular Function, Left / Q000187:drug effects* / Q000502:physiology
D004837:Epinephrine