L-carnitine does not exert any in vitro relaxant effect in Guinea pig trachea, lung parenchyma and human bronchial tissue.
The aim of the present study was to investigate the probable in vitro relaxant effect of carnitine in guinea pig trachea, guinea pig lung parenchymal strips, and human bronchial tissue. It was suggested by an in vivo study that carnitine pretreatment prevented the subclinic bronchospasm in children who underwent chronic hemodialysis. Tracheal and lung parenchymal preparations of 10 guinea pigs and 5 human bronchial tissues were prepared and mounted in 20-mL organ baths. In the first series of experiments, contractions to carbachol and histamine (10(-9) to 10(-3) M) were compared after the tissues were incubated with different concentrations of L-carnitine (10(-6) to 10(-4) M). pD(2) values were compared with analysis of variance (ANOVA) and P <.05 was considered as significant. In the second part of experiments, the inhibitory effect of L-carnitine (10(-9) to 10(-3) M) was investigated on the sustained contractions of preparations to carbachol (10(-6) M) and histamine (10(-5) M). In the first part of the study pD(2) values obtained with carbachol were 6.48 +/- 0.09, 5.42 +/- 0.05, and 6.48 +/- 0.02 for guinea pig trachea, guinea pig lung parenchymal strips, and human bronchial tissues, respectively. pD(2) values obtained with histamine were 5.34 +/- 0.10, 5.74 +/- 0.06, and 6.32 +/- 0.03 for guinea pig trachea, guinea pig lung parenchymal strips, and human bronchial tissues, respectively. No significant difference was observed between the pD(2) values before and after incubation with carnitine (P >.05). In the second part of the study, only 10(-4) M L-carnitine exerted an insignificant relaxant effect (6.16% +/- 1.22% on carbachol induced contractions and 4.48% +/- 0.85% on histamine induced contractions) in guinea pig trachea. Our results show that L-carnitine exerts no in vitro relaxant effect in guinea pig trachea, guinea pig lung parenchymal strips, and human bronchial preparations.
Uzuner
Nevin
N
Department of Pediatrics, Medical Faculty, Dokuz Eylul University, Balcova, Izmir, Turkey.
Kavukcu
Salih
S
Karaman
Ozkan
O
Apaydin
Sebnem
S
Göldeli
Esin
E
D000818:Animals; D001980:Bronchi / Q000187:drug effects*; D002217:Carbachol / Q000494:pharmacology; D002331:Carnitine / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008168:Lung / Q000187:drug effects*; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D009994:Osmolar Concentration; D013997:Time Factors; D014132:Trachea / Q000187:drug effects* / Q000502:physiology*
D006632:Histamine; D002217:Carbachol; D002331:Carnitine