The mechanism of water permeation across the sarcolemma was characterized by examining the kinetics and temperature dependence of osmotic swelling and shrinkage of rabbit ventricular myocytes. The magnitude of swelling and the kinetics of swelling and shrinkage were temperature dependent, but the magnitude of shrinkage was very similar at 6 degrees, 22 degrees, and 37 degrees C. Membrane hydraulic conductivity, Lp, was approximately 1.2 x 10(-10) liter.N-1.s-1 at 22 degrees C, corresponding to an osmotic permeability coefficient, Pf, of 16 microns.s-1, and was independent of the direction of water flux, the magnitude of the imposed osmotic gradient (35-165 mosm/liter), and the initial cell volume. This value of Lp represents an upper limit because the membrane was assumed to be a smooth surface. Based on capacitive membrane area, Lp was 0.7 to 0.9 x 10(-10) liter.N-1.s-1. Nevertheless, estimates of Lp in ventricle are 15 to 25 times lower than those in human erythrocytes and are in the range of values reported for protein-free lipid bilayers and biological membranes without functioning water channels (aquaporin). Evaluation of the effect of unstirred layers showed that in the worst case they decrease Lp by < or = 2.3%. Analysis of the temperature dependence of Lp indicated that its apparent Arrhenius activation energy, Ea', was 11.7 +/- 0.9 kcal/mol between 6 degrees and 22 degrees C and 9.2 +/- 0.9 kcal/mol between 22 degrees and 37 degrees C. These values are significantly greater than that typically found for water flow through water-filled pores, approximately 4 kcal/mol, and are in the range reported for artificial and natural membranes without functioning water channels. Taken together, these data strongly argue that the vast majority of osmotic water flux in ventricular myocytes penetrates the lipid bilayer itself rather than passing through water-filled pores.
Skip Nav Destination
Article navigation
1 April 1996
Article|
April 01 1996
Osmotic gradient-induced water permeation across the sarcolemma of rabbit ventricular myocytes.
M A Suleymanian,
M A Suleymanian
Department of Physiology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0551, USA.
Search for other works by this author on:
C M Baumgarten
C M Baumgarten
Department of Physiology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0551, USA.
Search for other works by this author on:
M A Suleymanian
Department of Physiology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0551, USA.
C M Baumgarten
Department of Physiology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0551, USA.
Online ISSN: 1540-7748
Print ISSN: 0022-1295
J Gen Physiol (1996) 107 (4): 503–514.
Citation
M A Suleymanian, C M Baumgarten; Osmotic gradient-induced water permeation across the sarcolemma of rabbit ventricular myocytes.. J Gen Physiol 1 April 1996; 107 (4): 503–514. doi: https://doi.org/10.1085/jgp.107.4.503
Download citation file:
Sign in
Don't already have an account? Register
Client Account
You could not be signed in. Please check your email address / username and password and try again.
Could not validate captcha. Please try again.
Sign in via your Institution
Sign in via your InstitutionSuggested Content
Email alerts
Advertisement