Related Experiment Videos
Refined membrane preparations mask ischemic fall in myocardial beta-receptor density
A A Wolff1, D K Hines, J S Karliner
1Cardiovascular Research Institute, University of California, San Francisco.
The American Journal of Physiology
|September 1, 1989
Summary
Crude myocardial preparations, like the 1,000-g pellet, better reflect beta-adrenergic receptor changes during ischemia than refined methods. This finding suggests using simpler methods for more relevant research on heart conditions.
Area of Science:
- Cardiology
- Molecular Biology
- Biochemistry
Background:
- Previous studies on ischemic myocardial beta-adrenergic receptors often discarded initial low-speed pellets.
- This practice may lead to the loss of relevant receptor data during acute ischemia.
Purpose of the Study:
- To investigate changes in beta-adrenergic receptor density during acute myocardial ischemia.
- To compare receptor density in different myocardial membrane preparations.
Main Methods:
- Studied beta-adrenergic receptor density (Bmax) using [125I]-iodocyanopindolol in rabbits undergoing 30 minutes of coronary occlusion.
- Analyzed receptor changes in a low-speed (1,000-g) pellet, a high-speed (40,000-g) pellet, and unspun myocardial homogenate.
Main Results:
- Bmax significantly decreased in the 1,000-g pellet during ischemia (46.8 to 21.6 fmol/mg protein).
- No significant change in Bmax was observed in the 40,000-g pellet (46.8 to 47.9 fmol/mg protein).
- Unspun homogenate also showed an ischemic decrease in Bmax (32.9 to 20.9 fmol/mg protein).
Conclusions:
- The 1,000-g pellet contains a substantial portion of myocardial beta-adrenergic receptors.
- Crude myocardial membrane preparations (1,000-g pellet or unspun homogenate) may offer greater pathophysiological relevance for studying ischemia than refined preparations.