EFFECT OF MAGNESIUM-FREE SOLUTIONS ON THE RESPONSES OF THE GUINEA-PIG URINARY-BLADDER TO ADENOSINE 5'-TRIPHOSPHATE AND NERVE-STIMULATION

Exposure of the guinea pig urinary bladder to magnesium-free Krebs-Henseleit type solution for 60 min led to an increase in the responses of the tissues to added adenosine 5'-triphosphate (ATP). The responses of the tissue to histamine were unaffected. The atropine-resistant contractions due to nerve stimulation were potentiated at frequencies above 4 Hz when the response of the tissue was 60% of its maximum response. This would suggest that, although ATP does contribute to the response of the tissue at high frequencies, it is not the transmitter of the noncholinergic nerves present in the bladder.