Effects of extended sidestream smoke exposure on components of the C-fiber axon reflex.
We have previously shown that young guinea pigs repeatedly exposed to sidestream cigarette smoke (SS) develop decreased airway reactivity of the C-fiber system without changing reactivity to one of its neurotransmitters, substance P (SP). This study was designed to determine whether the decreased reactivity was due to decreased responsiveness to another neurotransmitter, neurokinin A (NKA), decreased lung SP content, decreased affinity or number of NK1 receptors, and/or decreased number of C-fibers. Duncan Hartley guinea pigs were exposed to filtered air (FA) or to SS for 6 h/day, 5 days/week for 5 weeks starting at 1 week of age. SS exposure did not change, (1) airway reactivity to NKA injected into the pulmonary artery of their isolated perfused lungs (n = 6-7 each group), (2) lung SP content as measured by enzyme immunoassay (n = 12 each group), (3) NK1 receptor number or affinity as measured by radioligand binding (n = 7 each group), or (4) SP-immunoreactive nerve profiles of the terminal bronchioles or small airways (n = 6 each group). Thus, SS exposure does not decrease C-fiber system by reducing NKA responsiveness, decreasing SP content, changing NK1 receptors, or decreasing the number of C-fibers.
Joad
J P
JP
School of Medicine, Department of Pediatrics, University of California at Davis, USA.
Avadhanam
K P
KP
Watt
K C
KC
Kott
K S
KS
Bric
J M
JM
Pinkerton
K E
KE
D016902:Air Pollution, Indoor; D000403:Airway Resistance / Q000187:drug effects; D000704:Analysis of Variance; D000818:Animals; D001980:Bronchi / Q000187:drug effects / Q000378:metabolism; D006168:Guinea Pigs; D007124:Immunoenzyme Techniques; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007269:Injections, Intra-Arterial; D008168:Lung / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009412:Nerve Fibers / Q000187:drug effects* / Q000378:metabolism; D015288:Neurokinin A / Q000008:administration & dosage / Q000633:toxicity*; D011651:Pulmonary Artery / Q000187:drug effects; D011869:Radioligand Assay; D013373:Substance P / Q000378:metabolism; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
D014028:Tobacco Smoke Pollution; D013373:Substance P; D015288:Neurokinin A