Question

Under what circumstance would the heart produce significant levels of adenosine?

Under what circumstance would the heart produce significant levels of adenosine?

Myocardial hypoxia

Aerobic exercise

Increased heart rate

Bradycardia

Answer 1

The heart produces adenosine significantly in the circumstances of myocardial hypoxia.

Hypoxia means a lack of oxygen. When heart tissue doesn't get the proper amount of oxygen, causing hypoxia. And one of the main reasons for hypoxia is ischemia, blockage in vessels that leads to slow blood flow. So adenosine works as a vasodilator. It dilates the vessels so that blood flow becomes normal and blood can carry the right amount of oxygen to the heart. Hypoxia is a serious condition for heart, it can lead to heart cell damage which of course heart will not want to happen so when hypoxia occurs, the heart starts producing adenosine significantly by breaking down ATP to get free from hypoxia.

Adenosine production during aerobic exercise is not like hypoxia. During exercise, oxygen demand is increased so the heart produces adenosine so that it can dilate the vessels and more amount of oxygen reach the heart. So here adenosine is produced in that amount that heart needs during exercise time.  

At the time of increasing heart rate, adenosine also produces because it also reduces the heart rate. But the amount is not significant like hypoxia but higher than aerobic excersice.

And in the case of bradycardia heart will not produce adenosine because bradycardia means slow heart rate and adenosine also deceased heart rate so the heart will not want to stop itself. So it will not produce adenosine.