Bronchopulmonary C-fibers modulate the breathing pattern in surfactant-depleted juvenile cats.
The aim of this study was to investigate the influence of nonmyelinated C-fibers on the breathing pattern by cooling the vagal nerves to temperatures at which myelinated nerve transmission from pulmonary stretch receptors is blocked (+7 degrees C) and further at which nonmyelinated fiber input is blocked (0 degrees C), in anaesthetized spontaneously breathing juvenile cats with normal (L(N)), surfactant-depleted (L(D)) and surfactant-treated (L(T)) lungs. In L(N), vagal cooling from +7 to 0 degrees C decreased respiratory frequency (f(R); -8%; p < 0.01), and increased tidal volume (V(T); +40%; p < 0.01). In the presence of shallow fast breathing in L(D), f(R) decreased (+38 to +7 degrees C: -26%; p < 0.015 and +7 to 0 degrees C: -24%; p < 0.001) and V(T) increased (+37%; p < 0.049 and +88%; p < 0.016). In L(T), f(R) decreased (+7 to 0 degrees C: -21%; p < 0.001), whereas V(T) remained the same at 0 degrees C (+12%; NS). These findings show for the first time that the activity of bronchopulmonary C-fibers have a prominent role in modulating the breathing pattern in juvenile cats with surfactant-depleted lungs.
Rieger-Fackeldey
Esther
E
Department of Women's and Children's Health, Section for Pediatrics, Uppsala University, Uppsala, Sweden. esther.fackeldey@kbh.uu.se
Sindelar
Richard
R
Sedin
Gunnar
G
Jonzon
Anders
A
D000704:Analysis of Variance; D000818:Animals; D001980:Bronchi / Q000294:innervation*; D018893:Bronchoalveolar Lavage / Q000379:methods; D002415:Cats; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology*; D010812:Physical Stimulation; D011663:Pulmonary Surfactants / Q000378:metabolism* / Q000494:pharmacology; D012119:Respiration / Q000187:drug effects; D013696:Temperature; D013990:Tidal Volume / Q000187:drug effects / Q000502:physiology; D014630:Vagus Nerve / Q000502:physiology
D011663:Pulmonary Surfactants