title: Relationship between intracellular calcium and airway reactivity in guinea pigs.
abstract: The present study was carried out to examine the relationship between intracellular free calcium ion concentrations and its regulatory enzymes, sodium potassium adenosine triphosphatase (Na(+),K(+)-ATPase) and calcium adenosine triphosphatase (Ca(2+)-ATPase), with airway reactivity to inhaled histamine in guinea pigs. Forty-nine guinea pigs were included in this study. Of these, 34 animals responded to histamine bronchoprovocation challenge in vivo with a greater than 35% fall in specific airways conductance and were labeled as "reactive," and the remaining 15 were "nonreactive." The dose of histamine producing a 35% fall in specific airways conductance was labeled as ED(35) SGaw. The animals were then sacrificed, and the following biochemical measurements were carried out: intracellular free calcium ion concentrations [Ca(2+)](i) in leukocytes and isolated tracheal smooth muscle cells, activities of Na(+),K(+)-ATPase and Ca(2+)-ATPase in tracheal homogenate, and plasma levels of lysophosphatidylcholine (LPC). Reactive guinea pigs showed significantly higher [Ca(2+)](i) and Na(+),K(+)-ATPase and Ca(2+)-ATPase activities. Airway reactivity (ED(35) SGaw) had significant negative correlation with [Ca(2+)](i), with activities of each of the ATPases and with plasma lysophosphatidylcholine. It is concluded that the level of [Ca(2+)](i) is an important determinant of airway reactivity. Intracellular calcium levels modulate airway response to histamine with higher levels being associated with greater reactivity.
authors.affiliation: Department of Biochemistry, Delhi University, Delhi-110 007, India.
authors.forename: D
authors.initials: D
authors.lastname: Jain
authors.forename: H G
authors.initials: HG
authors.lastname: Raj
authors.forename: S V
authors.initials: SV
authors.lastname: Gangal
authors.forename: S K
authors.initials: SK
authors.lastname: Chhabra
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D001249:Asthma / Q000503:physiopathology*; D002118:Calcium / Q000494:pharmacology*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D004195:Disease Models, Animal; D005260:Female; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D007424:Intracellular Fluid / Q000737:chemistry; D008297:Male; D012137:Respiratory System / Q000187:drug effects; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
chemical_list: D006632:Histamine; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium