. "Aquaporin-1 (AQP1) passively transports carbon dioxide (CO2) across the plasma membrane according to the concentration gradient (Nakhoul et al. 1998, Blank & Ehmke et al. 2003, Endeward et al. 2006, Musa-Aziz et al. 2009). The pore in AQP1 that conducts CO2 may be distinct from the pore that conducts water."^^ . . . . . . .