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Differential functional and molecular effects on lymphatic pumping in aged‐rat mesenteric lymphatics and thoracic duct
Author(s) -
Gashev Anatoliy A,
Muthuchamy Mariappan
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a279-a
Subject(s) - lymphatic system , chronotropic , contractility , lymphatic vessel , contraction (grammar) , anatomy , thoracic duct , inotrope , vascular smooth muscle , medicine , endocrinology , biology , chemistry , pathology , smooth muscle , blood pressure , heart rate , cancer , metastasis
The mechanisms of age‐related changes in lymphatic pumping remain unclear. The general objectives of this study were to characterize the lymphatic intrinsic contractile activity during aging and to investigate the age‐dependent changes in the contractile machinery of lymphatic muscle. Active lymphatic pump parameters were evaluated in experiments with isolated, cannulated and pressurized rat mesenteric lymphatics (ML) and thoracic ducts (TD) taken from adult (9 mo) and old (24 mo) rats (Fischer‐344 NIA). Both aged ML and TD exhibited a decreased tonic and inotropic (contraction amplitude) responses to the increases of transmural pressure, but chronotropic (contraction frequency) reactions remained rather intact. We also found that age‐related changes developed differentially in regional lymphatic beds. Particularly lymphatics that usually behave more as pumping vessels (ML) affected by aging in larger degree than predominantly conductive TD. Molecular analyses found that both cardiac and vascular α‐actin expression is decreased significantly in TD of 24 months old rats when compared to 9 months‐old samples. Furthermore, smooth muscle MHC gene analyses showed reduced expression of SM1 MHC in both ML and TD in aged samples. In addition protein analyses in TD isolated from aged animals demonstrated that both tropomyosins as well as vascular actin were reduced. (Supported by TAMU CERH 5 P30 ES09106‐08)