Fig 1.
H1 receptor activation increased vascular permeability.
The effects of diphenhydramine (Diphe) or cimetidine (Cime), 2-pyridylethylamine (Pyri) on vascular hyperpermeability. (A) Photographs of representative mouse ears. (B) Quantification of Evans blue leakage (n = 4–6). (C) Quantification of ear thickness (n = 4–6). #P < 0.05, as compared with IgE. (D) Quantification of Evans blue leakage after compound 48/80 (C48/80) application (n = 4–6). (E) Quantification of Evans blue leakage after histamine application (n = 4–7). *P < 0.05, compared with vehicle. #P < 0.05, compared with histamine. Data are presented as mean ± SEM.
Fig 2.
Two types of vasculature are in mouse ear.
(A) Observation point. (B) Whole-mount immunostaining of PECAM-1, α-SMA, and desmin in the proximal vessel (magnification, ×200). Bar, 100 μm. A, artery; V, vein. (C) Whole-mount immunostaining of PECAM-1, α-SMA, desmin, and FCεRI in the capillary (magnification, ×200). Bar, 100 μm. Dotted lines indicate the edge of ear.
Fig 3.
Histamine increased blood flow volume.
(A) Typical images of the proximal vessel region before and 5 min after histamine treatment (magnification, ×100). Bar, 200 μm. Solid lines indicate vein. Dotted lines indicate artery. Ovoid circles indicate the FITC-dextran leakage. (B) Quantification of the FITC-dextran leakage after histamine application (n = 6–12). (C) Typical images of histamine-induced relaxation (magnification, ×200). Bar, 100 μm. A, artery; V, vein. (D) Quantification of the change in vessel diameter (n = 6–12). (E) Measurement of blood flow 5 min after histamine application using laser doppler velocimetry (n = 8). Measurement of blood flow (F) and blood flow velocity (G) before and 5 min after histamine application using in vivo microscopy (n = 15). *P < 0.05, compared with vehicle. #P < 0.05, compared with histamine. Data are presented as mean ± SEM.
Fig 4.
L-NAME or phenylephrine pretreatment inhibited histamine-induced hyperpermeability and vascular relaxation.
(A) Effect of L-NAME pretreatment or endothelium on the histamine-induced relaxation of mesenteric artery. (B) Effect of diphenhydramine or cimetidine pretreatment on the histamine-induced relaxation of mesenteric artery(n = 4–5). (C) Effect of L-NAME or phenylephrine (Phe) on histamine-induced vascular hyperpermeability. Typical photographs showing extravasation of Evans blue after histamine treatment. (D) Quantification of the Evans blue leakage (n = 4–7). (E) Quantification of the ear thickness (n = 4–6). (F) Quantification of arterial diameter changes (n = 6–12). *P < 0.05, compared with vehicle. #P < 0.05, compared with histamine. Data are presented as mean ± SEM.
Fig 5.
Histamine regulated endothelial barrier function in vivo.
(A) Whole-mount immunostaining of VE cadherin in the ear vessel (magnification, ×400). Bar, 10 μm. (B) Fluorescence intensity of VE-cadherin at endothelial cell junction in ear vessel (n = 4–5). (C) En face immunostaining of VE-cadherin in the pulmonary artery (magnification, ×400). Bar, 10 μm. *P < 0.05, compared with vehicle. Data are presented as mean ± SEM.
Fig 6.
Histamine regulated endothelial barrier function in vitro.
(A) Typical graph of histamine treatment in HDMECs. (B) Quantification of TER in HDMECs (n = 4–8). (C) Effects of pretreatment with diphenhydramine, cimetidine, Y27632, and bisindolylmaleimide 1 on the histamine-induced change in transendothelial electric resistance (TER) in HDMECs (n = 4–6). (D) Effect of pretreatment with L-NAME on the histamine-induced change in TER in HDMECs (n = 4). *P < 0.05, compared with non-treated control. #P < 0.05, compared with histamine. Data are presented as mean ± SEM.