Related Experiment Videos
Timed dose-response relationship of depressive action of ouabain on toad heart contraction in vitro
Abstract:
Timed dose-response relationship (TDRR) of depressive action of ouabain (Oua) 0.01-30 mmol.L-1 on toad heart contraction in vitro was studied by simultaneous recordings of mechanical tension and electrocardiography. It was found that the inhibition of contraction tension, the latency, the half equilibrium time of depression, and the cardioplegia time (CPT) were all concentration-dependent (P < 0.01). The EC50 +/- L95 of Oua was 35 +/- 8 mumol.L-1, in which L95 is the average 95% confidence limit. The TDRR data of latency or CPT were fitted to the hyperbolic 4-parameter model II weighted with the square of SE inversely: Y = 25.9492(7.2757)/(1nX + 23.5906)(6.2757) + 72.7732 for latency and Y = 20637.37/(1nX + 3.0947)(3.5907) + 196.7069 for CPT. It was concluded that the hyperbolic type of TDRR was present in Oua depressive action on the toad heart contraction in vitro.
Insights
Ouabain (Oua) exhibits a concentration-dependent depressive effect on toad heart contractions in vitro. This study reveals a hyperbolic timed dose-response relationship for ouabain
Area of Science:
- Pharmacology
- Cardiovascular Physiology
- Toxicology
Background:
- Ouabain is a cardiac glycoside known for its effects on heart contractility.
- Understanding the dose-response relationship is crucial for assessing its cardiac effects.
Purpose of the Study:
- To investigate the timed dose-response relationship (TDRR) of ouabain's depressive action on isolated toad heart contractions.
- To characterize the concentration-dependent effects of ouabain on cardiac mechanical tension and electrography.
Main Methods:
- Simultaneous recordings of mechanical tension and electrocardiography were performed.
- Toad hearts were exposed to varying concentrations of ouabain (0.01-30 mmol.L-1).
- Data were analyzed using a hyperbolic 4-parameter model to fit latency and cardioplegia time.
Main Results:
- Ouabain demonstrated a significant concentration-dependent inhibition of contraction tension, latency, and cardioplegia time (P < 0.01).
- The EC50 for ouabain was determined to be 35 ± 8 μmol.L-1.
- Hyperbolic models accurately described the TDRR for latency and cardioplegia time.
Conclusions:
- A hyperbolic TDRR characterizes the depressive action of ouabain on toad heart contraction in vitro.
- These findings provide quantitative insights into the kinetics of ouabain's cardiac effects.