Split-drop filtration rates in lung capillaries. (a) Plots are data from single capillaries held at Pc = 3 cmH₂O. Infusion conditions are none (left), or hyperosmolar sucrose for 1 minute (middle) or 15 minutes (right). Δ split-drop volume, change from initial split-drop volume. (b) Data are responses to barrier-enhancing agonists in relation to the indicated infusion conditions. *P < 0.05 as compared with bar on immediate left. (c) Responses before and after hyperosmolar urea infusion (450 mosm). (d) Barrier responses in capillaries given 15-minute infusions with agents as indicated or with no agent (control [ctl]). Split-drop responses were obtained following infusion. *P < 0.05 compared with control; **P < 0.05 compared with isosmolar condition. (e) Responses to TNF-α before (control) and after 15-minute hyperosmolar infusion at indicated periods. *P < 0.05 compared with control. (f) Responses to TNF-α before (control) and after hyperosmolar infusions of different durations. *P < 0.05 compared with control. For determination of filtration rate, the oil drop was split by the indicated agents in 4% albumin (split-drop solution). Mean ± SD; n = 3, each bar. iso, isosmolar Ringer’s buffer (300 mosm); hyp, hyperosmolar sucrose (350 mosm); thr, thrombin (7 units/ml); TNF, TNF-α (200 ng/ml); H₂O₂ (100 μM); jsp, jasplakinolide (100 nM) alb, albumin; lat, latrunculin B (100 nM); gen, genistein (50 μM).