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Molecular and functional analyses of the contractile apparatus in lymphatic muscleLymphatics are necessary for the generation and regulation of lymph flow. Lymphatics use phasic contractions and extrinsic compressions to generate flow; tonic contractions alter resistance. Lymphatic muscle exhibits important differences from typical vascular smooth muscle. In this study, the thoracic duct exhibited significant functional differences from mesenteric lymphatics. To understand the molecular basis for these differences, we examined the profiles of contractile proteins and their messages in mesenteric lymphatics, thoracic duct, and arterioles. Results demonstrated that mesenteric lymphatics express only SMB smooth muscle myosin heavy chain (SM-MHC), whereas thoracic duct and arterioles expressed both SMA and SMB isoforms. Both SM1 and SM2 isoforms of SM-MHC were detected in arterioles and mesenteric and thoracic lymphatics. In addition, the fetal cardiac/skeletal slow-twitch muscle-specific beta-MHC message was detected only in mesenteric lymphatics. All four actin messages, cardiac alpha-actin, vascular alpha-actin, enteric gamma-actin, and skeletal alpha-actin, were present in both mesenteric lymphatics and arterioles. However, in thoracic duct, predominantly cardiac alpha-actin and vascular alpha-actin were found. Western blot and immunohistochemical analyses corroborated the mRNA studies. However, in arterioles only vascular alpha-actin protein was detected. These data indicate that lymphatics display genotypic and phenotypic characteristics of vascular, cardiac, and visceral myocytes, which are needed to fulfill the unique roles of the lymphatic system.
Document ID
20040087765
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Muthuchamy, Mariappan
(College Station Texas 77843-1114, United States)
Gashev, Anatoliy
Boswell, Niven
Dawson, Nancy
Zawieja, David
Delp, Z.
Date Acquired
August 21, 2013
Publication Date
May 1, 2003
Publication Information
Publication: The FASEB journal : official publication of the Federation of American Societies for Experimental Biology
Volume: 17
Issue: 8
ISSN: 0892-6638
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Musculoskeletal

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