Cholesterol is the main regulator of the CO permeability of biological membranes.

We present here a compilation of membrane CO2 permeabilities (Pco(2)) for various cell types from the literature. Pco(2) values vary over more than two orders of magnitude. Relating Pco(2) to the cholesterol content of the membranes shows that, with the exception of red blood cells, it is essentially membrane cholesterol that determines the value of Pco(2). Thus, the observed strong modulation of Pco(2) in the majority of membranes is caused by cholesterol rather than gas channels.