lymphatics - 11. Nozaki, K., M. A. Moskowitz, K. I....

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11. Nozaki, K., M. A. Moskowitz, K. I. May- nard, N. Koketsu, T. Dawson, D. S. Bredt, and S. H. Snyder. Possible origins and distribution of immunoreactive nitric oxide synthase-containing nerve fibers in cerebral arteries. J. Cereb. Blood Flow Metab. 13: 70-79, 1993. 12. Nunokawa, Y., N. Ishida, and S. Tanaka. Cloning of inducible nitric oxide synthase in rat vascular smooth muscle cells. Bio- them. Biophys. Res. Commun. 191: 89-94, 1993. 13. Pou, S., W. S. Pou, D. S. Bredt, S. H. Snyder, and G. Rosen. Generation of superoxide by purified brain nitric oxide synthase. J. Biol. Chem. 267: 24173-24176, 1992. 14. Toda, N., and T. Okamura. Role of nitric oxide in neurally induced cerebroarterial relaxation. J. Pharmacol. Exp. Ther. 258: 1027-1032,1991. 15. Yoshizumi, M., A. Perrella, J. C. Burnett, Jr., and M.-E. Lee. Tumor ne- crosis factor downregulates an endothe- lial nitric oxide synthase mRNA shortening its half-life. Circ. Res. 73: 205-209, 1993. Fluid Pump Mechanisms in Initial Lymphatics Geert W. Schmid-SchMbein and Benjamin W. Zweifach Initial lymphatics are noncontractile and drain into collecting lymphatics with a smooth muscle intima, valves, and peristalsis. How does interstitial fluid enter the initial lymphatics? Introduction The function of the lymphatics as a drainage and immune-surveillance system has been recognized for well over a century. Key aspects of its operation have evaded, however, a conclusive analysis. While the gen- eral pathway of plasma motion fluid ultrafiltration across the vascu- lar wall into the interstitium and the transport of lymph fluid along chains of contractile lymphangions with valves have enjoyed widespread ac- ceptance, the mechanism by which interstitial fluid finds its way into the dispersed set of initial lymphatics has remained speculative (1). This aspect of the problem is the focus of this report. Lymphatic microanatomy The sine qua non for an under- standing the lymphatic filling mech- standing the lymphat ic filling mech- anism is a detailed picture of the microanatomy. Nume Numerous ultrastruc- rous ultrastruc- tural studies have aided in this effort, tural studies have aide ed in this effort, especially in regard to the lymph vessels that are positioned in the are pos itioned interstitium and are the first entry points of interstitial fluid into the lymphatic system. Although the de- system. Al .though the de- G. W. Schmid-Schijnbein and B. W. Zweifach vided into two major classes: the are in the Institute for Biomedical Engineering initial lymphatics and the collecting at the University of California, San Diego, Rr;n. lymphatics (Fig. 1). This terminology 5601 Engineering Building, 9500 Gilman Dr., does not necessarily conform to def- La Jolla, CA 92093-0412, USA. initions used in the past, but it is a FIGURE 1. Schematic display of initial lymphatics draining into collecting lym- phatics in cat mesentery. Initial lymphatics exhibit no active contractions and are in pat paired with arteriolar venular ar- cades. Their network density is low in com- parison with density of capillary meshwork (not shown). Collecting lymphatics exhibit active peristalsis and are usually not paired with blood vessels.
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This note was uploaded on 09/14/2011 for the course PHARM cs taught by Professor Staff during the Spring '11 term at UCSD.

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lymphatics - 11. Nozaki, K., M. A. Moskowitz, K. I....

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