Comparison of the determinants in the differences in force-frequency relationships between rat and rabbit left atria.
- Author:
Chang Mann KO
1
;
Soon Jin KIM
Author Information
1. Department of Pharmacology, Wonju-College of Medicine, Yonsei University, 162 Ilsan-Dong, Wonju, Kangwon-Do, South Korea. changmko@wonju.yonsei.ac.kr
- Publication Type:Original Article
- MeSH:
Animals;
Heart;
Monensin;
Norepinephrine;
Prevalence;
Rats*;
Sarcoplasmic Reticulum
- From:The Korean Journal of Physiology and Pharmacology
2000;4(5):417-425
- CountryRepublic of Korea
- Language:English
-
Abstract:
The underlying mechanism commonly applicable for both the positive and negative force-frequency relationships (FFR) was pursued in left atria (LA) of rat and rabbit. The species differences in the roles of Na+/Ca2+ exchanger and sarcoplasmic reticulum (SR), which are major intracellular Ca2+ regulatory mechanisms in the heart, were examined in the amplitude accommodation to the frequency that changed from 3 Hz to the variable test frequencies for 5 minutes in the electrically field stimulated left atria (LA) of rat and rabbit. Norepinephrine strongly increased the frequency-related amplitude accommodation in both of rat and rabbit LA, while monensin, oubain or the reduced Na+ and 0 mM Ca2+ containing Tyrode solution increased the frequency-related amplitude accommodation only in the rabbit LA. Monenisn was also able to increase the frequency-related amplitude accommodation only in 1-day old rat LA but not in 4-week old rat LA that had 75% less Na+/Ca2+ exchanger with 97% higher SR than 1-day old rat LA. Taken together, it is concluded that the differences in the prevalence between myocardial Na+/Ca2+ exchanger and SR in the amplitude accommodation to the frequency-change determine the difference in the FFR between rat and rabbit heart.
