and ethylene glycol uptake of X. laevis oocytes expressing HsAQP3 or DrAqp3b. (A) PEG of oocytes expressing different amounts of cRNA (1-40 ng) encoding HsAQP3 or DrAqp3b. Control oocytes were injected with 50 nl of water. The PEG was measured by swelling measurements during 20 sec in isotonic MBS containing 60 mM of ethylene glycol at pH 7.5. Values are the mean ± SEM of three experiments (n = 8-10 oocytes for each aquaporin). Data with an asterisk at the same cRNA dose are significantly different (Student's t test, p < 0.01). (B) Uptake of radiolabeled ethylene glycol of oocytes injected with 50 nl of water or 5 ng of HsAQP3 or DrAqp3b cRNA. Oocytes were exposed to isotonic MBS containing 1 mM cold ethylene glycol and 5 μM radiolabelled [1,2-3H]ethylene glycol for 1 min. Values (mean ± SEM; n = 8-10 oocytes) with different superscript are significantly (ANOVA, p < 0.01).