Nonuniform effects of histamine on small pulmonary vessels in cats

Abstract

In in vivo cat lung, using an X-ray TV system, we analyzed responses in internal diameter (ID), flow velocity, and volume flow of arteries and veins (100-500 microns ID) to histamine (8-15 micrograms/kg iv) under three conditions. With histamine alone, three types of ID response (constriction, dilatation, and no change) occurred in parallel-arranged arteries. Relative frequency and magnitude of constriction were maximum in arteries of 300-400 micron ID, whereas those of dilatation were maximum in arteries of 100-200 micron ID. In veins, relatively uniform constriction occurred. Under H2-blockade, histamine caused greater constriction than that with histamine alone in arteries and veins of 300-500 micron ID. Under beta-blockade, with histamine, ID of all vessels decreased significantly below the ID sizes under the above two conditions, and no dilatation occurred. In two parallel arteries that showed opposite ID changes to histamine, flow velocity increased, but volume flow decreased in a constricted artery while it increased in a dilated one. Those data indicated that, with histamine, qualitatively and quantitatively nonuniform ID response was induced in both parallel- and series-arranged small pulmonary arteries and, in turn, produced heterogeneous flow distribution. Factors to cause the nonuniformity may be partly explained by difference in density of H2- and beta-receptors in vascular walls.

Characterization of the histamine receptors in the guinea‐pig lung: evidence for relaxant histamine H3 receptors in the trachea

“…The responses to histamine in isolated vascular preparations vary considerably depending upon the species (Toda, 1986), the type of vessels (Van de Voorde & Leusen, 1984) and the region within the vascular bed from which the tissue has been derived (Shirai et al, 1987;Tsuru et al, 1987). In the present study, arteries from various parts of the pulmonary vascular tree were examined, but only small intraregional differences in the histamine-induced contractile response were seen.…”

H1‐ and H2‐receptor characterization in the tracheal circulation of sheep

“…Thus, in the cat, histamine constricts pulmonary arteries with internal diameter of between 300 and 400Mm and dilates pulmonary arteries with internal diameter less than 200pM. The small pulmonary veins are also constricted (Shirai et al, 1987). Therefore, in preparations containing a mixture of different histamine-sensitive vessels, histamine must have a very complex action.…”

“…Histamine dilates the tracheal vasculature in dogs and this effect is dose-related (Laitinen et al, 1987c). However, in view of the considerable species variation in the responses to histamine of airway smooth muscle (Simonsson & Svedmyr, 1981) and pulmonary vessels (Shirai et al, 1987), we have examined the effect of this mediator on the tracheal circulation in sheep using the method previously described for dogs (Laitinen et al, 1987b). We have also investigated the receptor mechanisms which mediate the actions of histamine and of specific H1-and H2-agonists on the tracheal circulation.…”

Functions and Control of the Pulmonary Circulation

“…Histamine, a major product released during mast cell degranulation, also has variable effects on pulmonary vascular tone, causing vasoconstriction in some animal models but vasodilation in others. [84][85][86][87] Serotonin released by activated platelets causes pulmonary vasoconstriction, notably in the presence of intravascular coagulation and thrombosis. In addition to its vasoconstriction properties, serotonin can promote pulmonary smooth muscle proliferation, suggesting a role in the pulmonary vascular remodeling observed with chronic pulmonary hypertension.…”