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The effects of activated complement on myocardial performance in vitro
P J Hendry1, G C Taichman, G P Biro
1University of Ottawa Heart Institute, Ottawa Civic Hospital, Canada.
Insights
Activated complement, a key immune system component, was investigated for direct effects on heart muscle (myocardium). This study found no direct impact of activated complement on myocardial performance in vitro.
Area of Science:
- Immunology
- Cardiovascular Physiology
Background:
- The complement system, a crucial part of innate immunity, plays a role in various organ dysfunctions.
- Its direct impact on myocardial function remains largely unexplored.
Purpose of the Study:
- To investigate whether activated complement directly affects myocardial contractility.
- To assess the functional integrity of human atrial trabeculae exposed to activated complement.
Main Methods:
- Human right atrial trabeculae were studied in vitro under isometric conditions.
- Trabeculae were exposed to four solutions: Tyrode's, autologous blood, plasma, and denatured plasma.
- Complement activation was induced using Zymosan, with complement activity assessed by CH50 levels.
Main Results:
- Complement activation was confirmed in blood and plasma solutions (p < 0.05).
- No significant differences were observed in resting forces, developed forces, or decay rates between groups.
- Myocardial functional integrity remained unaffected across all tested solutions.
Conclusions:
- Activated complement does not exert a direct influence on myocardial performance.
- The study provides evidence against a direct role of complement in acute myocardial dysfunction.
Abstract:
Activated complement has been implicated in the dysfunction of several organ systems, but can it directly affect the myocardium? This possibility was studied using human right atrial trabeculae contracting isometrically "in vitro" in four solutions: Tyrode's (T), autologous arterial blood (B), plasma (P) and denaturated plasma (DP). Complement was activated by the addition of Zymosan while vehicle alone was used as control. Complement activation occurred in the blood and plasma solutions, as assessed by a significant drop in CH50 (p less than 0.05), while there was no detectable complement activity in either T or DP. Myocardial functional integrity was assessed by the change in contractile parameters with time. Subsequent resting forces, relative developed forces (DF), and rates of decay of DF were similar between muscles contracting in the four solutions. We conclude that activated complement has no direct effect on myocardial performance.