Related Experiment Videos
Adenosine receptors mediating cardiac depression
Life Sciences
|November 29, 1982
Summary
Adenosine analogs, like l-phenylisopropyladenosine and N-cyclohexyladenosine, significantly reduced heart rate and contractility in guinea pigs. These effects are primarily mediated by A1-receptors and can be blocked by theophylline and 1,3-diethyl-8-phenylxanthine.
Area of Science:
- Pharmacology
- Cardiovascular Physiology
Background:
- Adenosine is a key endogenous nucleoside influencing cardiac function.
- Adenosine receptors, particularly A1 subtypes, are implicated in regulating heart rate and contractility.
Purpose of the Study:
- To investigate the effects of various adenosine analogs on cardiac rate and contractility.
- To determine the receptor subtype mediating adenosine's cardiac depressant effects.
Main Methods:
- Isolated guinea pig atria were used to assess the impact of adenosine analogs.
- Concentration-response relationships were established for different adenosine agonists.
- The effects of antagonists like theophylline and 1,3-diethyl-8-phenylxanthine (DPX) were evaluated.
Main Results:
- (-)-N-(1-methyl-2-phenylethyl) adenosine (l-PIA) and N-cyclohexyladenosine (CHA) demonstrated potent cardiac depressant effects at nanomolar concentrations.
- Other analogs, including d-phenylisopropyladenosine (d-PIA), showed weaker effects.
- Theophylline and DPX successfully antagonized the cardiac depressant actions of CHA and l-PIA.
Conclusions:
- The findings strongly suggest that the cardiac depressant effects of adenosine are mediated through A1-receptors.
- Specific adenosine analogs exhibit varying potencies, highlighting receptor subtype selectivity.
- Adenosine receptor antagonists can effectively reverse adenosine-induced cardiac depression.