Effect of histamine on lung contractile elements in growing cattle.
OBJECTIVE
To determine the effect of histamine on the contractile elements of the respiratory tract in neonatal calves and young adult cattle.


METHODS
Samples of trachealis muscle, bronchi, and intrapulmonary arteries and veins dissected from the respiratory tracts of healthy bovids (2 to 8 days and 16 to 20 months old).


METHODS
Histamine cumulative concentration-effect curves (10(-6) to 10(-3) M) were constructed in duplicate smooth muscle samples mounted in organ baths. Contractile responses to histamine were compared with reference contractions elicited by methacholine (10(-5) M) for airways or KCl (127 mM) for vessels.


RESULTS
In young adult cattle, trachealis muscle had a substantial contractile response to histamine (84% of methacholine-induced contraction), whereas bronchi reacted slightly (15 and 20% for large and small bronchi, respectively). Although contractile responses to KCl were comparable in arteries and veins, histamine-induced contractions were greater for intrapulmonary veins than for arteries (202 vs 48% of KCl-induced contraction). In neonatal calves, histamine-induced contraction of veins also exceeded that of arteries (230 vs 54% of KCl-induced contraction); however, unlike in young adult cattle, histamine produced notable contraction of large and small bronchi (48 and 60% of methacholine-induced contraction, respectively).


CONCLUSIONS
Compared with intrapulmonary arteries, intrapulmonary veins have greater contractile responses to histamine in neonatal and young adult cattle. Data suggest loss of histamine responsiveness in bronchial smooth muscle as neonatal calves grow to young adults. Venodilation may be useful in treatment of lung edema in cattle.
Jolly
Sandra
S
Department of Morphology and Pathology, Faculty of Veterinary Medicine, University of Liège, B43 Sart-Tilman, B-4000 Liège, Belgium.
Robinson
N Edward
NE
Desmecht
Daniel J
DJ
D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D001980:Bronchi / Q000187:drug effects / Q000502:physiology; D002417:Cattle / Q000254:growth & development*; D004305:Dose-Response Relationship, Drug; D006632:Histamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D008168:Lung / Q000098:blood supply / Q000187:drug effects* / Q000502:physiology*; D009119:Muscle Contraction; D011651:Pulmonary Artery / Q000187:drug effects / Q000502:physiology; D011667:Pulmonary Veins / Q000187:drug effects / Q000502:physiology; D012119:Respiration / Q000187:drug effects
D006632:Histamine