Key Points
- To quantitatively determine the geometric ultrastructural dimensions and membrane surface areas of compartments involved in the intramyocardial transfer of blood-borne substances in the intact rabbit heart.
- Examined glutaraldehyde-perfusion fixed rabbit hearts using quantitative histological sectioning and tailored mathematical modeling.
- Characterized the elliptical cross-sectional geometry of myocardial capillaries to calculate true capillary diameter and cellular barrier thicknesses.
- Corrected mean capillary diameter was 5.21 ± 1.41 µm, with effective diffusion widths of 187 ± 7 nm for the endothelial cell and 160 ± 10 nm for the pericapillary interstitium.
- Cardiomyocytes occupied 73.07% of myocardial tissue volume, followed by capillaries (9.36%), non-pericapillary interstitium (5.97%), large vessels (5.92%), pericapillary interstitium (1.94%), endothelium (1.83%), interstitial cells (0.96%), and t-tubules (0.95%).
- Normalized to total myocardial volume, surface areas were 75.2 ± 5.5 × 10³ m²/m³ for luminal endothelium, 82.2 ± 6.0 × 10³ m²/m³ for abluminal endothelium, and 89.1 ± 6.5 × 10³ m²/m³ for opposing cardiomyocyte membranes.
Structured PICO
PPopulationglutaraldehyde-perfusion fixed adult rabbit hearts
IInterventionquantitative assessment of geometric ultrastructural dimensions by means of histological and tailored mathematical techniques
OOutcomegeometric ultrastructural dimensions of myocardial compartments and parts thereof, and the membranes separating these compartmentssurrogate
This study provides detailed quantitative ultrastructural dimensions of the adult rabbit heart, which is important for modeling cardiac uptake and intramyocardial transfer of blood-borne substances.