Digital vascular responses to intra-arterial injections of bradykinin, kallidin, and eledoisin in man.

DOISIN are vasoactive polypeptides recently synthesized in pure form.1-3 Bradykinin and kallidin exist in man, whereas eledoisin has been found only in the posterior salivary glands of Eledone. Although the three poly-peptides have potent vasodilating and hypo-tensive properties, only bradykinin and kallid-in are closely related structurally (fig. 1). The nonapeptide structure of bradykinin was established by Boissonnas and associates4 in 1960. Pierce and Webster5 and Werle and associates6 concluded independently that kal-lidin is a decapeptide and suggested that it is the lysine-homologue of bradykinin, a fact later confirmed by Nicolaides and his co-workers.2 Bradykinin and kallidin are both released from the alpha-2-globulin in man.7 Eledoisin was first isolated from the posterior salivary glands of two molluscan species, Eledone moschata and Eledone aldrovandi, by Erspamer and Anastasi8 in 1961 and synthesized by Boissonnas and Sandrin3 in 1962. Eledoisin is an endecapeptide with an amino acid sequence markedly different from that of bradykinin and kallidin (fig. 1). Interest in the vasoactive polypeptides has been aroused because of the role that they may play in local vascular control; however, relatively few studies of the influence of bradykinin, kallidin, and eledoisin on the circulation have been performed on man. In 1958, Fox and Hilton9 showed that bradykinin was released in the upper extremity when the trunk and lower extremity were heated. They suggested that bradykinin was responsible for functional hyperemia of the sweat glands during heating. Fox and associates'0 found that intra-arterial injection of bradykinin resulted in an increase in blood flow to the forearm and hand. DeFreitas and associates" found that the intravenous infusion of brady-kinin decreased systemic arterial pressure and peripheral vascular resistance and increased cardiac output in man. Similar observations were made by Kontos and co-workers'2 during intravenous infusions of eledoisin into man. They also observed an increase in hand and forearm blood flow during intravenous injection of eledoisin. Kontos and colleagues concluded that the general circulatory effects of eledoisin resemble those of bradykinin, but eledoisin is a much more potent vasodilator in man. In a previous report from this laboratory,13 the digital vascular responses to the ipsilateral intra-arterial (brachial) injection of bradykin-in in man were described as follows: (1) flushing of the digit, (2) increase in skin temperature, (3) increase in the magnitude of the volume pulse wave, (4) decrease in digital inflow volume of blood, and (5) increase in the total volume of the digit. These responses are similar …