ABSTRACT
The effects of sodium fluoride [NaF] on the isolated pulmonary arterial rings and the isolated tracheal strips of rats as well as the effect of long-term oral administration of NaF on the response pulmonary arterial rings and tracheal strips to biogenic amines were investigated. NaF concentrations of 3, 5 and 10 mM produced a concentration dependent contraction in isolated pulmonary arterial rings and in tracheal strips of rats. NaF-induced contractions were reduced after pretreatment with nifedipine or melatonin. Aminophylline produced significant decline in NaF-induced contraction of isolated pulmonary arterial rings. Phentolamine, atropine, chlorpheniramine, indomethacin, NDGA or L-NAME did not produce any alteration in the NaF-induced contractions. Chronic oral NaF administration produced significant decline in the response of the isolated pulmonary arterial ring and isolated tracheal strips to serotonin [5-HT] and acetylcholine [ACh], respectively. Histopathological examination of iso1ated trachea and lung of treated rats showed marked damage. In conclusion, the results of the present study suggest that calcium channel and/or release of free radicals may mediate the contractile effects of fluoride in isolated pulmonary arterial rings and in tracheal strips. Furthermore, chronic oral fluoride administration causes damage to tracheal and pulmonary tissues and thus, care should be taken to avoid ingestion of large amount of fluoride especially in children