Cardiovascular effects of a potent opioid peptide, (D-Met2, Pro5)-enkephalinamide.

The cardiovascular effects of morphine and a potent enkephalin analogue, D-Met2, Pro5-enkephalinamide (D-Met2, Pro5-EA) have been examined in pentobarbitone anesthetized cats with their vagi cut and in awake normotensive and genetically hypertensive rats. In cats both opioids only moderately decreased the blood pressure and the heart rate, but the enkephalin analogue considerably attenuated the carotid occlusion pressor response. Neither substance influenced the blood pressure and the heart rate in normotensive rats, but both induced moderate hypotension and considerable bradycardia in spontaneously hypertensive rats, the potency of D-Met2, Pro5-EA being much stronger than that of morphine.