Vasculature portal vein

Once schistosome cercariae penetrate the skin of their host, they can remain in this environment as schistosomula for up to 5 days before entering the vasculature and beginning their migration to the lungs and, subsequently, the hepatic portal vein (Wilson, 1987). During this journey, which may take 3 weeks (Wilson, 1987), and thereafter, schistosome parasites must contend with an assortment of host immune factors. Yet, as is well known, these parasites are able to complete the journey to their final destination and live for years. Research has shown that schistosomes have adapted a variety of mechanisms that enable them to evade a strong and potentially lethal host immune response. 

Whether this can explain the mechanism of the selectivity seen with BRL 55834 (32) and rimakalim (33) remains to be proved. Certainly, the studies which have been reported using smooth muscle cells from the portal vein need to be extended to airways smooth muscle. This is particularly important for BRL 55834 (32) which has been reported to activate two K channels in bovine airways smooth muscle and shows selectivity for the airways relative to levcromakalim (2). Similarly, it will be interesting to ascertain whether the selectivity for the vasculature found with compounds... 

The spleen is the largest of all lymphatic tissues and rests against the lower ribs (nine through eleven), the diaphragm, the stomach, and the left kidney in the left hypochondral region. A parenchyma of red and white pulp is surrounded by a capsule of fibrous connective tissue that contains efferent lymphatics, blood vessels, nerves, and some smooth muscle. The red pulp is a cordal and sinusoidal system concerned primarily with the production of blood products. The while pulp, which is lymphoid tissue, produces ihymus-dependent T lymphocytes and B lymphocytes and plasma cells. The latter components produce the humeral antibody component of the immune system, and the T-lymphocytes are involved in the cell-mediated arm of the system. The vasculature consists of the splenic artery, the largest branch from the celiac trunk, and the splenic vein, which unites with the mesenteric vein to form the portal vein. 

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