Isolated human cystic artery: responses to common agonist and antagonist drugs

The extramural artery of the human gall bladder (cystic artery), a small artery (outside diameter 1.3 +/- 0.03 mm) with a thick muscular wall and little elastin within the tunica media, has catecholamine fluorescence localized to the adventitia-medial border. Isolated helical strips of the artery are responsive to norepinephrine (NE), 5-hydroxytryptamine (5HT) and vasopressin (VP) at low concentrations, but at the maximal frequency of transmural electrical stimulation used (16 Hz), the response is only 10--20% of the NE maximum response. Phentolamine (2.7 X 10(-6) M) antagonized responses to NE, 5HT and, to a lesser degree, electrical stimulation and these actions are similar to those reported in other mammalian tissue. In vitro use of reserpine (1.6 X 10(-5) M) and guanethidine (4 X 10(-5) M) also produced effects which were predictable from effects observed in other mammalian tissues; except reserpine diminished responsiveness to NE and 5HT and guanethidine enhanced responses to the early administered electrical stimulation.