Abstract
Angiotensin ll (Ang ll) is produced locally in the lungs and may potentiate airway responsiveness in asthmatic patients. Ang ll induces its effects by activating two GPCR subtypes: AT1 and AT2. This lab has previously found that AT1 antagonist losartan reduces airway inflammation and reactivity. The AT2 receptors counterbalance the effects of AT1 and are known to be anti‐inflammatory. However, it is not known if AT2 receptors have any effects in asthma. We studied the effects of AT2 agonist novokinin and antagonist PD 12339 administered in vivo in a mouse model of asthma. Mice were divided into control (non‐allergic; CON) and allergen sensitized‐challenged (SEN) groups, and were sensitized i.p. on days 1, 6 with 0.2μg ovalbumin (OVA) followed by 5% OVA aerosol challenges on days 11–13. Whole body plethysmography (measuring airway responsiveness as enhanced pause, Penh) and bronchoalveolar lavage (BAL) studies were performed. Methacholine (MCh; 48mg/ml) produced significantly higher airway responsiveness in allergic mice compared to control (563.71±40% in SEN vs. 208.79±20.84% in CON, p<0.05). However, novokinin (i.p. 0.3mg/kg) treated SEN mice had significantly attenuated MCh‐indcued airway responsiveness (563.71±40% in SEN vs. 252±11% in SEN+Novokinin, p<0.001). The AT2 antagonist PD 12339 (i.p.5mg/kg) significantly increased MCh airway responsiveness (563.71±40% in SEN vs. 757±30% in SEN+PD 12239, p<0.05). Differential BAL cell analysis showed novokinin also decreased eosinophils (221±21 in SEN vs. 122±18 in SEN+PD 12239, p<0.001), while PD 12239 had no effect on eosinophils (245± 16 cells in SEN+PD 12339). Our data suggests that activation of AT2 receptors may attenuate airway reactivity and inflammation in our model of asthma.Support or Funding InformationLong Island University start‐up funds (DSP)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Published Version
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