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Both protein and blood cells reduce coronary microvascular permeability to macromolecules
Insights
Adding protein and blood cells to Krebs perfusate stabilizes isolated rat hearts. This blood-cell and protein-rich solution reduces macromolecular leakage, maintaining coronary microvascular permeability for better cardiac function.
Area of Science:
- Cardiovascular Physiology
- Microcirculation Research
- Organ Perfusion Studies
Background:
- Isolated Krebs-perfused hearts show functional decline, edema, and increased coronary resistance over time.
- Perfusion with filtered blood offers greater stability compared to Krebs solution.
- Observed changes in Krebs hearts suggest a permeability-edema may be involved.
Purpose of the Study:
- To investigate if adding protein and blood cells to Krebs perfusate impacts coronary microvascular permeability to macromolecules.
- To quantify transcoronary macromolecular leakage in a rat heart model.
Main Methods:
- Utilized a rat heart preparation for direct visualization and quantification of transcoronary macromolecular leakage.
- Introduced fluorescent albumin (FITC-BSA) after initial perfusion periods.
- Compared leakage rates across different perfusate compositions: Krebs, Krebs with albumin (BSA), and Krebs with BSA and blood cells.
Main Results:
- Severe transcoronary leakage of FITC-BSA observed with Krebs perfusate alone.
- Leakage significantly decreased with 2 g/100 ml BSA in the perfusate.
- Further reduction in leakage occurred upon adding washed blood cells to the perfusate.
- The O/I ratio for FITC-BSA exchange was 0.70 (Krebs), 0.55 (Krebs-BSA), and 0.45 (Krebs-BSA-blood cells), indicating significant effects (P < 0.05).
Conclusions:
- Both protein (albumin) and blood cells are crucial for maintaining the semipermeable nature of coronary exchange vessels.
- The addition of protein and blood cells to perfusate solutions enhances the stability of isolated hearts.
- These findings highlight the importance of a blood-like composition for preserving microvascular integrity in isolated organ preparations.
Abstract:
A number of studies report that isolated Krebs-perfused hearts deteriorate with time, develop edema, and demonstrate a progressive increase in coronary vascular resistance. However, hearts perfused with filtered blood are more stable with regard to cardiac function and coronary resistance. The changes observed in the Krebs hearts may be due to a "permeability"-type edema. The purpose of this study was to systematically determine whether adding protein and blood cells to a Krebs perfusate affected coronary microvascular permeability to macromolecules. The rat heart preparation employed allowed direct visualization and quantification of transcoronary macromolecular leakage. We observed severe transcoronary leakage of fluorescent albumin (FITC-BSA) when FITC-BSA was later added after 20 min of perfusion with Krebs. Leakage was decreased by including 2 g/100 ml albumin (BSA) in the initial perfusate but was not further reduced by increasing the BSA concentration to 5 g/100 ml. However, adding washed blood cells to the initial perfusate did further reduce FITC-BSA leakage. The index of FITC-BSA exchange, the O/I ratio, was 0.70 +/- 0.02 (+/- SE) for Krebs perfusate, 0.55 +/- 0.03 for Krebs-BSA, and 0.45 +/- 0.02 for Krebs-BSA-blood cells, indicating significant effects for both protein and blood cells (P less than 0.05). The results suggest that both protein and blood cells are necessary to maintain the semipermeable characteristics of the coronary exchange vessels.