Fig. 1.

Type I (TI) cells have the capacity to take up Cl⁻. Cl⁻ uptake was measured in freshly isolated rat TI cells both in the absence and in the presence of terbutaline (10⁻⁴ M) at 30 s, 5 min, and 10 min. Cl⁻ uptake increased between 30 s and 10 min in both groups, but at 5 min, Cl⁻ uptake in terbutaline-treated cells was 31% greater than in untreated cells (n = 4 cell isolations, *P < 0.05). Uptake was measured in pmol Cl⁻/μg protein and graphically represented as %change of control ± SE. In these experiments, control was defined as Cl⁻ uptake in unstimulated TI cells (no terbutaline) at 30 s. In terbutaline-stimulated cells, uptake increased significantly by 110% between 30 s and 5 min (**P < 0.05).