Vascular smooth muscle contractility assays for inflammatory and immunological mediators

Abstract

The blood vessels are one of the important target tissues for the mediators of inflammation and allergy; futher cytokines affect them in a number of ways. We review the use of the isolated blood vessel mounted in organ baths as important source of pharmacological information. While its use in the bioassay of vasoactive substances tends to be replaced with modern analytical techniques, contractility assays are effective to evaluate novel synthetic drugs, generating robust potency and selectivity data about agonists, partial agonists and competitive or insurmountable antagonists. For instance, the human umbilical vein has been used extensively to characterize ligands of the bradykinin B 2 receptors. Isolated vascular segments are live tissues that are intensely reactive, notably with the regulated expression of gene products relevant for inflammation (e.g., the kinin B 1 receptor, inducible nitric oxide synthase). Further, isolated vessels can be adapted as assays of unconventional proteins (cytokines such as interleukin-1, proteases of physiopathological importance, complement-derived anaphylatoxins, recombinant hemoglobin) and to the gene knockout technology. The well known cross-talks between different cell types, e.g., endothelium-muscle, nerve terminal-muscle, can be extended (smooth muscle cell interaction with resident or infiltrating leukocytes, tumor cells). Drug metabolism and distribution problems can be modeled in a useful manner using the organ bath technology, which, for all these reasons, opens a window on an intermediate level of complexity relative to cellular and molecular pharmacology on one hand, and in vivo studies on the other.

Gastrointestinal Congestion Dilates the Hepatic Artery Through the P38 MAPK Signal Transduction Pathway During Liver Transplantation

“…This result is consistent with other experiments demonstrating that inflammatory cytokines can influence ring tension. 13,14 Based on the results showing that vasorelaxation induced by gastrointestinal congestion plasma could be partially reversed by indomethacin, glibenclamide, BAY 11-7082, and SB 203580 and the results showing that hepatic artery rings treated with this plasma expressed higher levels of phospho-P38 MAPK protein and P38 MAPK mRNA, we concluded that the No, PgI 2 , the K ATP channel, NF-κB, and the P38 MAPK signal transduction pathway were involved in the vasorelaxation induced by this type of plasma.…”

Vasopeptidase-activated latent ligands of the histamine receptor-1

“…The preparation of the umbilical vein rings was described elsewhere [20]. This vein is a suitable contractile bioassay for both the B 2 R and H 1 R [13,14]. After a 2.5-h equilibration period during which tissues were periodically washed with fresh Krebs buffer, tissues were randomly assigned to one of the experimental groups in several protocols further described in Results.…”

“…Thus, the potency of L-alanyl-histamine as a contractile agent in the isolated vein (Fig. 5B) is determined by the enzymatic velocity of the APN, the diffusion rates of the pro-drug into, and that of the produced histamine out of the tissue and, possibly, by histamine degradation within the tissue (the general problem of non-equilibrium pharmacological effects on isolated tissues is discussed elsewhere [14]). …”

“…1) was tested as a latent H 1 R agonist activable by aminopeptidase N (APN, CD13, EC 3.4.11.2), on the model of the standard chromogenic substrate of APN, L-Alap-nitroanilide [12]. In addition to molecular studies based on recombinant B 2 R and H 1 R, we exploited the human umbilical vein contractility assay naturally expressing these two receptor types that mediate important contractile responses [13,14]. This vein also expresses ACE [2,15].…”

Met-Lys-bradykinin-Ser-Ser, a peptide produced by the neutrophil from kininogen, is metabolically activated by angiotensin converting enzyme in vascular tissue

“…These and other isolated tissues are suitable to identify activating and inactivating pathways in the sense that local metabolism distorts the concentration-effect relationship of agonist peptides. Indeed, the concentration of these peptides at the vicinity of receptors in the smooth muscle is not necessarily in equilibrium with that present in the bathing fluid of the tissue, the rate of metabolic change caused by peptidases within the tissue being occasionally faster than the rate of agonist diffusion from the bathing fluid to the extracellular space of the tissue (this paradigm is illustrated with several examples relevant for peptide receptor ligands elsewhere [6]). We provide evidence for the paradoxical activation of Met-Lys-BK-Ser-Ser by ACE in vascular tissue.…”