Isoproterenol-induced facilitation of norepinephrine release does not primarily involve a local angiotensin II mechanism in guinea pig pulmonary arteries.

We have attempted to clarify whether or not captopril and 1Sar-8Ile-angiotensin II could protect isoproterenol-induced facilitation of norepinephrine release in guinea pig pulmonary arteries loaded with 3H-norepinephrine. Angiotensin I at 1 nM and 30 nM isoproterenol similarly facilitated evoked release of 3H-norepinephrine at 1 Hz. Captopril at 1 microM and 1Sar-8Ile-angiotensin II at 10 nM completely prevented angiotensin I-induced facilitation, whereas these pretreatments produced no effect on isoproterenol-induced facilitation. Isoproterenol-induced facilitation of norepinephrine release does not primarily involve a local angiotensin II mechanism.