No abstract

The effect of the endogenous cannabinoid anandamide on K ϩ currents activated by the ATP-sensitive potassium (K ATP ) channel opener cromakalim was investigated in follicle-enclosed Xenopus oocytes using the two-electrode voltage-clamp technique. Anandamide (1-90 M) reversibly inhibited cromakaliminduced K ϩ currents, with an IC 50 value of 8.1 Ϯ 2 M. Inhibition was noncompetitive and independent of membrane potential. Coapplication of anandamide with the cannabinoid type 1 (, or pertussis toxin (5 g/ml) did not alter the inhibitory effect of anandamide, suggesting that known cannabinoid receptors are not involved in anandamide inhibition of K ϩ currents. Similarly, neither the amidohydrolase inhibitor phenylmethylsulfonyl fluoride (0.2 mM) nor the cyclooxygenase inhibitor indomethacin (5 M) affected anandamide inhibition of K ϩ currents, suggesting that the effects of anandamide are not mediated by its metabolic products. In radioligand binding studies, anandamide inhibited the specific binding of the K ATP ligand [ 3 H]glibenclamide in the oocyte microsomal fractions, with an IC 50 value of 6.3 Ϯ 0.4 M. Gonadotropin-induced oocyte maturation and the cromakalim-acceleration of progesterone-induced oocyte maturation were significantly inhibited in the presence of 10 M anandamide. Collectively, these results indicate that cromakalim-activated K ϩ currents in follicular cells of Xenopus oocytes are modulated by anandamide via a cannabinoid receptor-independent mechanism and that the inhibition of these channels by anandamide alters the responsiveness of oocytes to gonadotropin and progesterone.

The effect of cocaine on K+ currents activated by the KATP channel opener cromakalim was investigated in follicular cells of Xenopus oocytes. The results indicate that cocaine in the concentration range of 3-500 microM reversibly inhibits cromakalim-induced K+ currents. The IC50 value for cocaine was 96 microM. Inhibition of the cromakalim-activated K+ current by cocaine was noncompetitive and voltage independent. Pretreatment with the Ca2+ chelator BAPTA did not modify the cocaine-induced inhibition of cromakalim-induced K+ currents, suggesting that Ca2+-activated second messenger pathways are not involved in the actions of cocaine. Outward K+ currents activated by the application of 8-Br-cAMP or forskolin were also inhibited by cocaine. The EC50 and slope values for the activation of K+ currents by cromakalim were 184+/-19 microM and 1.14 in the absence of cocaine as compared to 191+/-23 microM and 1.03 in the presence of cocaine (300 microM). Cocaine also blocked K+ currents mediated through C-terminally deleted form of Kir6.2 (KirDeltaC26) in the absence of sulfonylurea receptor with an IC50 value of 87 microM, suggesting that cocaine interacts directly with the channel forming Kir6.2 subunit. Radioligand binding studies indicated that cocaine (100 microM) did not affect the binding characteristics of the KATP ligand, [3H]glibenclamide. These results demonstrate that cromakalim-activated K+ currents in follicular cells of Xenopus oocytes are modulated by cocaine.

The local injection of GM-CSF improved impaired wound healing in adriamycin-treated rats.

Twenty-three percent of patients in our study developed lung metastases. As the grade of the disease increased, metastases-free intervals are shortened. Although it has been reported that lung metastases in patients with extremity sarcomas may present as solitary or multiple nodules in earlier trials with radiographic screening methods, the current review of 400 patients found that a substantial number of patients may present radiological appearances other than nodular formations.