Relationship between cftr genotypes and PV curves. Littermates from 30–60 days of age were genotyped and individuals with cftr+/+ (Black), cftr+/- (Green), and cftr-/-(Red) were evaluated using pressure volume curve analysis at Peeps of 0, 3, and 6. A: PV curve at PEEP 3; B: Calculated Cst for all PV curves; C: Calculated hysteresis for PV curves in A. All measures were corrected individually for lung weight. Error bars are +/- standard deviation. *p < 0.05 when compared to cftr+/+ and **p < 0.05 when compared to cftr+/-.