Effect of long-term tilt on mechanical and electrical properties of rat saphenous vein. Am J Physiol 1989 Apr;256(4 Pt 2):H1185-91
Date
04/11/1989Pubmed ID
2705557DOI
10.1152/ajpheart.1989.256.4.H1185Scopus ID
2-s2.0-0024602004 (requires institutional sign-in at Scopus site) 46 CitationsAbstract
Femoral vein pressure in adult male Sprague-Dawley rats kept in specially designed tubelike cages rose immediately from a control value of 2.9 +/- 0.2 (SE) mmHg to a gravity-induced sustained value of 5.9 +/- 0.2 mmHg on initiation of a 2-wk 45 degrees head-up tilt period. Femoral arterial pressure was not altered by tilting. In 2 wk mean external diameter, but not total wall thickness, of in vitro distal saphenous vein segments from tilted rats was increased approximately 30% above that of segments from nontilted controls at each of four successive 5-mmHg intralumenal pressure (IP) increments applied between 0 and 20 mmHg. Consequently, in tilted rats isobaric stress was increased 38% at low and 24% at high IP, whereas incremental distensibility was decreased at mid IP. Vascular smooth muscle (VSM) in tilted rat vein, but not artery, was hyperpolarized relative to controls both in vitro at normal physiological pressures [membrane potential (Em) = -58.2 +/- 0.8 vs. -52.4 +/- 0.8 mV, respectively] and in situ during local neural blockade (Em = -61.3 +/- 2.3 vs. -53.5 +/- 0.5 mV, respectively). The conclusion is that a moderate chronic elevation of IP in a vein results in hyperpolarization of its VSM and an elevation of its total capacity due to an as yet unexplained mechanism of physiological adaptation.
Author List
Monos E, Contney SJ, Cowley AW Jr, Stekiel WJAuthor
Allen W. Cowley Jr PhD Professor in the Physiology department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Adaptation, PhysiologicalAnimals
Gravitation
Male
Membrane Potentials
Muscle, Smooth, Vascular
Rats
Rats, Inbred Strains
Saphenous Vein
Stress, Mechanical
Venous Pressure