Related Experiment Videos
Phospholipase D increases cell surface Ca2+ binding and positive inotropy in rat heart
The American Journal of Physiology
|November 1, 1984
Summary
Phospholipase D (PLD) treatment increases anionic phospholipids (AP) in heart cell membranes, enhancing calcium binding and contractility. This suggests AP plays a key role in regulating heart muscle force and calcium flux.
Area of Science:
- Cardiology
- Biochemistry
- Cell Biology
Background:
- Anionic phospholipids (AP) in the sarcolemma are implicated in calcium (Ca2+) binding.
- Increased Ca2+ binding may influence myocardial contractility.
Purpose of the Study:
- To investigate the effect of increased AP content on Ca2+ binding and contractility in heart cells.
- To test the hypothesis that AP influences Ca2+ flux and force development.
Main Methods:
- Cultured neonatal rat myocardial cells were treated with phospholipase D (PLD).
- Exchangeable Ca2+ and Ca2+ bound to AP were quantified.
- Contractility of neonatal rat ventricular tissue was measured.
- Spontaneous electrical activity was assessed.
Main Results:
- PLD treatment increased total exchangeable Ca2+ by 36%.
- Ca2+ bound to AP increased by 85%, measured by polymyxin B displacement.
- Myocardial contractility increased 1.7- to 2.5-fold.
- Spontaneous electrical activity remained unchanged.
Conclusions:
- Increased AP content in the sarcolemma enhances Ca2+ binding.
- PLD-induced increase in AP leads to significantly increased cardiac contractility.
- Ca2+ bound to anionic sarcolemmal phospholipids is crucial for controlling transsarcolemmal Ca2+ flux and cardiac force generation.