Possible role of cAMP, cGMP and [Ca2+]i during NANC relaxation in the cat airway smooth muscle

Isometric responses of isolated intrapulmonary bronchioles from cats with and without adult heartworm infection

“…Also known as serotonin, 5hydroxytryptamine is a mediator released from mast cells that is well known to cause airway smooth muscle constriction in many species, including cats, in vitro and in vivo. 8,16,17 Serotonin antagonism induced with cyproheptadine does not attenuate airway inflammation in cats with experimentally induced asthma. 8 However, cyproheptadine treatment did reduce the maximal KCl response of tracheal and bronchiolar smooth muscle rings from cats with experimentally induced asthma, and endogenous release of serotonin was increased in response to antigen stimulation, suggesting that serotonin sensitizes the bronchiolar response in this model.…”

“…The lack of difference between the 2 groups suggests that cyclic guanosine monophosphate-mediated signaling pathways causing smooth muscle relaxation are not different in heartworm-infected cats. Studies 16,17,23,24,26 evaluating the effects of nonadrenergic-and noncholinergic-mediated airway relaxation in cats reveal that nitric oxide-and cyclic guanosine monophosphatemediated pathways and vasoactive intestinal peptideand adenosine 3',5'-cyclic monophosphate-mediated pathways are both important mechanisms of nonadrenergic-and noncholinergic-mediated airway relaxation. Vasoactive intestinal peptide was not evaluated in the present study and could be a future area of comparison between heartworm-infected and control cats.…”

Effects of intravenous and subcutaneous heartworm homogenate from doxycycline-treated and untreated donor dogs on bronchial reactivity and lung in cats

“…In heartworm-infected cats, the opposite response is noted in that heartworm-infected cats and IV homogenate cats were hyporesponsive to the contractile agonist ACh and 5-HT. Serotonin is a mediator from mast cells known to cause airway smooth muscle constriction in cats and most species (Schooley et al, 2007, Altiere et al, 1984, Imoto et al, 1998. A change in the receptors density or an inherent blocking of contraction is more probable with bronchial remodeling with adult heartworms, but is a consideration based on the present study with no significant bronchial remodeling.…”