Spontaneous activity in peripheral diaphragmatic lymphatic loops.
Am J Physiol Heart Circ Physiol
; 305(7): H987-95, 2013 Oct 01.
Article
em En
| MEDLINE
| ID: mdl-23893166
ABSTRACT
The spontaneous contractility of FITC-dextran-filled lymphatics at the periphery of the pleural diaphragm was documented for the first time "in vivo" in anesthetized Wistar rats. We found that lymphatic segments could be divided into four phenotypes 1) active, displaying rhythmic spontaneous contractions (51.8% of 197 analyzed sites); 2) stretch-activated, whose contraction was triggered by passive distension of the vessel lumen (4.1%); 3) passive, which displayed a completely passive distension (4.5%); and 4) inert, whose diameter never changed over time (39.6%). Smooth muscle actin was detected by immunofluorescence and confocal microscopy in the vessel walls of active but also of inert sites, albeit with a very different structure within the vessel wall. Indeed, while in active segments, actin was arranged in a dense mesh completely surrounding the lumen, in inert segments actin decorated the vessels wall in sparse longitudinal strips. When located nearby along the same lymphatic loop, active, stretch-activated, and passive sites were always recruited in temporal sequence starting from the active contraction. The time delay was â¼0.35 s between active and stretch-activated and 0.54 s between stretch-activated and passive segments, promoting a uniform lymph flux of â¼150/200 pl/min. We conclude that, unlike more central diaphragmatic lymphatic vessels, loops located at the extreme diaphragmatic periphery do require an intrinsic pumping mechanism to propel lymph centripetally, and that such an active lymph propulsion is attained by means of a complex interplay among sites whose properties differ but are indeed able to organize lymph flux in an ordered fashion.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Mecanotransdução Celular
/
Vasos Linfáticos
/
Contração Muscular
/
Músculo Liso
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
Am J Physiol Heart Circ Physiol
Assunto da revista:
CARDIOLOGIA
/
FISIOLOGIA
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
Itália