Role of histamine in airway remodeling of asthmatic guinea pig / 生理学报

To investigate the role of histamine in airway remodeling, 50 healthy guinea pigs were divided into 5 groups: control group: nebulized inhalation of distilled water for 8 weeks; asthma model group: nebulized inhalation of ovalbumin (OVA) for 8 weeks after sensitization; continued asthma model group: nebulized inhalation of OVA for 14 weeks after sensitization; histamine group: nebulized inhalation of OVA for 14 weeks after sensitization and histamine was added in the last 6 weeks; antagonist group: nebulized inhalation of OVA for 14 weeks after sensitization and histamine receptor antagonists were added in the last 6 weeks. For each group, the concentration of histamine, sodium ion (Na(+)), chlorine ion (Cl(-)), arterial partial pressure of oxygen (PaO2), arterial partial pressure of carbon dioxide (PaCO2), pH, actual bicarbonate (AB), standard bicarbonate (SB) in serum, and thickness of airway mucosa, base membrane and smooth muscle were measured and compared with each other. The results showed that: (1) the concentration of histamine in serum and the thickness of airway increased, the following order was, the control group, the asthma model group, the continued asthma model group and histamine group (P<0.01); and the concentration of histamine in serum and the thickness of airway of antagonist group was lower than that of the continued asthma model group (P<0.05, 0.01). (2) PaO2 of the asthma model group was lower than that of the normal control group (P<0.01); PaO2, pH, AB, SB decreased, the following order was, the asthma model group, the continued asthma model group and the histamine group (P<0.01); and PaO2, pH, AB, SB of the antagonist group was higher than that of the continued asthma model group (P<0.01); but for PaCO2, the order was converse (P<0.01); For the concentration of Na(+) and Cl(-) in serum, there was no difference among these groups. It is concluded that: (1) Histamine is one of the mediators in the airway remodeling of asthma. (2) Histamine receptor antagonists may play a role in preventing and treating airway remodeling. (3) There is a negative correlation between the PaO2, pH and the wall thickness of the airway (P<0.01), while a positive correlation between the PaCO2, anion gap (AG) and the wall thickness of the airway (P<0.01).

Effects of histamine on endothelial nitric oxide synthase expression in pulmonary artery endothelial cells / 生理学报

All three nitric oxide synthase (NOS) isoforms are found in the lungs. It has been demonstrated that eNOS-derived NO plays an important role in modulating pulmonary vascular tone and inhibiting pulmonary vascular remodeling. Histamine induces pulmonary vasoconstriction by activating H(1)-receptor on the smooth muscle cells and vasodilation by stimulating H(2)-receptor. It remains unclear whether histamine also modulates the pulmonary vascular tone by regulating eNOS gene expression and NO production in pulmonary artery endothelial cells. Therefore, the present study was performed on cultured primary porcine pulmonary artery endothelial cells (PAECs) to investigate the effects of histamine on eNOS gene expression, and to explore the role of CaMK II in eNOS gene expression. After treatment with different concentrations histamine for different times, the levels of eNOS mRNA and protein were measured by RT-PCR and Western blot, respectively. The results showed that histamine upregulated eNOS mRNA and protein levels in a concentration- and time-dependent manner. Incubation with 10 micromol/L histamine for 24 h could increase eNOS mRNA and protein level to 160.8+/-12.2% (P<0.05) and 136.2+/-11.2% (P<0.05), respectively, of the control values. These up-regulation effects were prevented by selective CaMK II inhibitor, KN-93 (10 micromol/L). To investigate whether or not histamine increases eNOS expression by upregulating eNOS gene transcription, PAECs were transiently transfected with 1.6-kb fragment of the human eNOS promoter driving a luciferase reporter gene. The results suggested that eNOS gene promoter activity was enhanced to 148.2+/-33.7% (P<0.05) of the control after PAECs were incubated with 10 micromol/L histamine for 24 h. The nitrite and nitrate content in culture media measured by colorimetric method after incubation with 10 micromol/L histamine for 24 h indicated that the NO production in PAECs was increased. These results suggest that histamine up-regulates eNOS gene transcription and enhances NO production in PAECs by a signaling pathway involving CaMK II, which might be one of the mechanisms of histamine modulating pulmonary vascular tone.