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.
Caspi
J
J
Division of Cardiovascular Surgery, Hospital for Sick Children, Toronto, Canada.
Coles
J G
JG
Benson
L N
LN
Herman
S L
SL
Diaz
R J
RJ
Augustine
J
J
Brezina
A
A
Kolin
A
A
Wilson
G J
GJ
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