title: Atrazine increases the sodium absorption in frog (Rana esculenta) skin.
abstract: The presence of atrazine in agricultural sites has been linked to the decline in amphibian populations. The efforts of the scientific community generally are directed toward investigating the long-term effect of atrazine on complex functions (reproduction or respiration), but in the present study, we investigated the short-term effect on the short-circuit current (I(sc)), a quantitative measure of the ion transport operated by frog (Rana esculenta) skin. Treatment with 5 microM atrazine (1.08 mg/L) does not affect the transepithelial outfluxes of [14C]mannitol or [14C]urea; therefore, atrazine does not damage the barrier properties of frog skin. Atrazine causes a dose-dependent increase in the short-circuit current, with a minimum of 4.64 +/- 0.76 microA/cm2 (11.05% +/- 1.22%) and a maximum of 12.7 +/- 0.7 microA/cm2 (35% +/- 2.4%) measured at 10 nM and 5 microM, respectively. An increase in Isc also is caused by 5 microM ametryne, prometryn, simazine, terbuthylazine, or terbutryn (other atrazine derivatives). In particular, atrazine increases the transepithelial 22Na+ influx without affecting the outflux. Finally, stimulation of Isc by atrazine is suppressed by SQ 22536, H89, U73122, 2-aminoethoxydiphenyl borate, and W7 (blockers of adenylate cyclase, protein kinase A, phospholipase C, intracellular Ca2+ increase, and calmodulin, respectively), whereas indomethacin and calphostin C (inhibitors of cyclooxygenase and protein kinase C, respectively) have no effect.
authors.affiliation: Dipartimento di Fisiologia Generale ed Ambientale dell'Università di Bari, Via Amendola 165/A-70126 Bari, Italy. cassano@biologia.uniba.it
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Cassano
authors.forename: Vito
authors.initials: V
authors.lastname: Bellantuono
authors.forename: Concetta
authors.initials: C
authors.lastname: Ardizzone
authors.forename: Claudio
authors.initials: C
authors.lastname: Lippe
mesh_terms: D000818:Animals; D001280:Atrazine / Q000031:analogs & derivatives / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D006540:Herbicides / Q000633:toxicity*; D017136:Ion Transport / Q000187:drug effects; D011893:Rana esculenta; D015398:Signal Transduction; D012867:Skin / Q000737:chemistry; D012964:Sodium / Q000493:pharmacokinetics*
chemical_list: D006540:Herbicides; D012964:Sodium; D001280:Atrazine