Key Points
- This research aims to investigate how catecholamines influence contractility and oxygen consumption in excised dog hearts.
- Studied 11 excised cross-circulated dog hearts.
- Measured left ventricular contractility index (Emax) and the relationship between oxygen consumption (VO2) and systolic pressure-volume area (PVA).
- Administered adrenal medullary stimulation and exogenous epinephrine to evaluate their effects.
- Emax increased significantly with rising catecholamines, though sensitivity varied between hearts.
- The slope of the VO2-PVA locus was steeper than that of the reference relationship in control contractility.
- Exogenous epinephrine produced effects similar to those of adrenal medullary stimulation.
Structured PICO
PPopulation11 excised cross-circulated dog heart preparations (from 22 adult mongrel dogs)
IInterventionEndogenous catecholamines (via adrenal medullary stimulation) and exogenous epinephrine infusion
CComparatorBaseline control state
OOutcomeLeft ventricular contractility index (Emax) and the relationship between LV O2 consumption (VO2) and systolic pressure-volume area (PVA)surrogate
Endogenous and exogenous catecholamines similarly increase contractility and oxygen consumption in excised cross-circulated dog hearts, with wide individual variability in sensitivity.
Limitations
- Acute experiment
- Adrenal stimulation was always performed before exogenous infusion, potentially causing down-regulation or fatigue
- Adrenal stimulation released both epinephrine and norepinephrine, while exogenous infusion was epinephrine only