Question

Imagine the following hypothesis: Long-term, heavy coffee consumption (let's say coffee made from the Robusta beans grown in sub-Saharan Africa, so very high in caffeine) makes the person susceptible to cardiac arrest due to myocardial hypoxia. Describe a possible mechanism explaining this. Note: cardiac arrest is mentioned for dramatic effect. It has nothing to do with your answer. (6 pts)

Answer 1

The relaxation of the cardiac vascular smooth muscle cells occurs when the adenosine binds to the A2a receptor on the muscle wall which results into generation of the c-AMP and thus activates the protein kinases for hyperpolarisation and thus relaxation of the muscle .

The caffeine acts as a adenosine antagonist and causes competitive binding to the G-coupled receptor A2a causes decreases in cardiac vasodilation and stress and as a result it causes the insufficient blood flow to the cardiac muscle thus myocardial hypoxia. The prolonged myocardial hypoxia may cause cardiac arrhythmias and cardiac arrest.