Atropine [HSA]

In recent years, some studies indicates that atropine eye drops is one of the most effective interventions for myopia. Due to large demand, the use of low-concentration atropine eye drops to reduce myopia progression is popular in China. Considering that the underlying mechanism of atropine eye drops in controlling the progression of myopia is still unclear, it is reasonable to pay enough attention to whether the long-term use of atropine eye drops in children will increase the risk of dry eye.

Colonic intramuscular interstitial cells of Cajal (ICC-IM) are associated with cholinergic varicosities, suggesting a role in mediating excitatory neurotransmission. Ca(2+)release in ICC-IM activates Ano1, a Ca2+-activated Cl(-)conductance, causing tissue depolarization and increased smooth muscle excitability. We employed Ca(2+)imaging of colonic ICC-IM in situ, using mice expressing GCaMP6f in ICC to evaluate ICC-IM responses to excitatory neurotransmission. Expression of muscarinic type 2, 3 (M-2, M-3), and NK(1)receptors were enriched in ICC-IM. NK(1)receptor agonists had minimal effects on ICC-IM, whereas neostigmine and carbachol increased Ca(2+)transients. These effects were reversed by DAU 5884 (M(3)receptor antagonist) but not AF-DX 116 (M(2)receptor antagonist). Electrical field stimulation (EFS) in the presence of L-NNA and MRS 2500 enhanced ICC-IM Ca(2+)transients. Responses were blocked by atropine or DAU 5884, but not AF-DX 116. ICC-IM responses to EFS were ablated by inhibiting Ca(2+)stores with cyclopiazonic acid and reduced by inhibiting Ca(2+)influx via Orai channels. Contractions induced by EFS were reduced by an Ano1 channel antagonist, abolished by DAU 5884, and unaffected by AF-DX 116. Colonic ICC-IM receive excitatory inputs from cholinergic neurons via M(3)receptor activation. Enhancing ICC-IM Ca(2+)release and Ano1 activation contributes to excitatory responses of colonic muscles.