Electrophysiological Experiments with Activators

A better understanding of the activator-veratridine interaction would require single-channel experiments which, however, are scarce. In cultured cardiomyocytes a mixture of veratridine and ATX II induces, on steady depolarization, frequent openings to a low conductance substate (y=4.6 pS). This can be seen in veratridine alone only after voltage jumps and for a short time whereas in ATX II alone a different substate (7 11.5 pS) is observed. In the mixture the state of low conductance is often preceded by openings of the largest conductance pS all 

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Studies on these cloned transporter genes have begun to reveal residues and structural domains that are essential for transport function for both NTl and NT2. " In addition, electrophysiological experiments have confirmed that these parasite permeases, unlike the mammalian ENTs, are secondary active transporters that couple the thermodynamically favorable influx of protons to import of purines. This arrangement presumably allows the parasite to compete effectively for purines with its host and concentrate these essential nutrients in its cytosol. 

The quinolinone derivative, OPC-88117 (73), is yet another compound described as possessing both Class I and Class III electrophysiological activities. Studies in guinea-pig papillary muscle showed that OPC-88117 at 30 increased APDgo by about 15% and decreased F ,ax by only 4% however, at 100 /iM APDgo was prolonged by 23 % and was decreased by 23 % [206]. Further experiments in isolated rabbit hearts demonstrated that OPC-88117 increased atrio-His bundle (A-H) and His bundle-ventricle (H-V) conduction times and refractory periods with a profile that was similar to, but more potent than that of lidocaine [207]. 

LAG experiments on the composition of the sex pheromone of the horse-chestnut leafminer, Cameraria ohridella Deschka et Dimic (Lepidoptera, Gracillariidae, Lithocolletinae) showed that (9T )-tetradecenal and the stereoisomers of 8E, 10 )-tetradeca-8,10-dienal exhibited significant electrophysiological activity and could, therefore, be considered as possible minor pheromone components along with 8E, 10.Z)-tetradeca-8,10-dienal which is the major component. 

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