Regional differences in the response of isolated human vessels to vasoactive substances.

1. Crural, mesenteric and pulmonary vessels obtained during surgery were studied. Isometric tension was recorded and contractions were induced by potassium 127 mM (K), noradrenaline 18 microM (NA), prostaglandin F2 alpha 2.9 microM (F2 alpha), ergotamine 3.8 microM (Erg) or digoxin 1.0 microM (Dig). 2. Spontaneous myogenic activity was only observed in pulmonary veins. F2 alpha induced spontaneous activity in mesenteric arteries. 3. In all types of vessels, except in mesenteric arteries, the response to K+ had a greater amplitude than contractions developed by NA. Erg induced a slowly developing contraction in mesenteric veins but no contraction in mesenteric arteries. Dig induced a long-lasting monophasic response in arteries and a biphasic response in the veins. 4. After immersion for 30 min in a Ca-free medium the amplitudes to both NA and K+ were significantly reduced. The veins were more susceptible to the effects of Ca-deprivation than the arteries.