Premium
Electrophysiology of rat mesenteric lymphatic vessel contraction
Author(s) -
von der Weid PierreYves,
Zawieja David C.,
Davis Michael J.
Publication year - 2007
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.21.6.lb95-b
Subject(s) - lymphatic system , contraction (grammar) , isometric exercise , electrophysiology , anatomy , guinea pig , membrane potential , extracellular , spike potential , chemistry , biology , medicine , biophysics , depolarization , pathology , microbiology and biotechnology
In mammals, including humans, lymph is propelled centrally primarily via the phasic contractions of lymphatic vessels. Contractions are initiated in the lymphatic muscle by action potentials (APs), initiated by a pacemaker, proposed in guinea pig and sheep to involve spontaneous transient depolarizations (STDs). Although rat vessels have been consistently used to study lymphatic contractile function, to date no investigation of the electrophysiological origin of the lymphatic contractions has been performed in this species. Using intracellular microelectrode measurements, the aim of this study was to investigate membrane potential (Vm) of rat mesenteric lymphatics under resting conditions and under isometric distension. Data from guinea pig vessels were used for comparison. Under resting conditions, muscle Vm was −48±1 mV (n=12) and displayed STDs (mean amplitude 1.4 mV, frequency 30/min) and APs (frequency 3–12/min) at rates faster than in guinea pig. STDs were significantly decreased by niflumic acid and 2‐APB. APs were dependent on extracellular Ca 2+ and suppressed by nifedipine. Increases in isometric tension (0.1 to 1.5 mN) augmented contraction/AP frequency, but did not substantially alter Vm or AP amplitude. In conclusion, STDs and APs occurred in rat lymphatics with a pharmacology similar to that of guinea pigs. However, the frequency and subsequent contraction rates were higher in the rat. Supported by NIH & NSERC (Canada)