Re: Units for Vmax

From: Nick Holford <n.holford@auckland.ac.nz> Subject: Re: Units for Vmax Date: 21 Oct 1997 17:15:59 -0400 It seems clearer to me to multiply VM by V (volume of distribution) V*VM/(KM+C2)*C2 because the term V*VM/(KM+C2) can be thought of the clearance at that value of C2 and the rate out is CL*C2. But perhaps more importantly please consider that a useful property of a parameter is that is should not be confounded with other parameters in a model especially when these parameters have different mechanistic bases. If you define VM with units of conc/time instead of amount/time you are effectively confounding VM with V. Because V and Vmax have quite different structural (V) and functional (VM) biological origins I think it is preferable to use units of amount/time for VM.. -- Nick Holford, Dept Pharmacology & Clinical Pharmacology University of Auckland, Private Bag 92019, Auckland, New Zealand email:n.holford@auckland.ac.nz tel:+64(9)373-7599x6730 fax:373-7556 http://www.phm.auckland.ac.nz/Staff/NHolford/nholford.htm