Abstract:Nicotinic acetyicholine receptors play a major role in excitatory neurotransmission in insect CNSs and constitute an important target for insecticides. Here, we report the isolation and functional characterisation of two cDNAs encoding nicotinic acetyicholine receptor a subunits from a major insect pest, the peach-potato aphid Myzus persicae. These two subunits, termed Mpal and Mpa2, are respective structural homologues of the Drosophila Da2/Schistocerca gregaria aLl a-subunit pair and the Drosophila ALS a subunit. Xenopus oocyte expression confirmed that each Myzus subunit can form functional acetylcholine-or nicotine-gated channels. However, some electrophysiological and pharmacological properties of the Myzus subunits were distinct from those encoded by the corresponding Drosophila subunits. Coexpression of the Myzus subunits with the chick /32 subunit revealed other differences from the Drosophila system, as only very limited potentiation of agonist-induced currents was observed with Mpa2 and none with Mpal. Available data therefore indicate that structurally homologous insect nicotinic acetylcholine receptor a subunits from different species can exhibit distinctive physiological and pharmacological characteristics.

The membrane potential of ventral longitudinal muscles of Tenebrio molitor larvae was studied as a function of time and of cesium substituted for all or part of external potassium. The conventional microelectrode technique was applied. The mean value of resting potential was -47.4 mV in standard physiological saline which did not change significantly with time (90 min). Cesium caused, almost immediately, a significant hyperpolarization of membrane potential the magnitude of which depended on cesium concentration. The presence of external potassium enhanced the effectiveness of cesium action, resulting in more pronounced hyperpolarization. The effect of Cs ions was fully reversible upon washing. These data support the idea that inward potassium current can be activated at resting potential level, at least in some cells, including the muscles studied. It is presumed that this potassium current might have some contribution to the resting membrane potential generation in mealworm larva muscles. Key words Cesium 9 Membrane potential 9 Blocking of potassium inward current 9 Insect muscle Abbreviations [K § extracellular concentration of K ions 9 E,, resting membrane potential of a cell when bathed in normal saline 9 EKK + equilibrium potential -MP membrane potential 9 RP resting potential -SD standard deviation 9 SEM standard error of the mean

Systemic lupus erythematosus (SLE) is a chronic disease of connective tissue with multi-organ involvement. Manifestation in the nervous system is one of the most difficult symptoms to assess and interpret. The aim of the study is to indicate diagnostic problems in patients with SLE in whom neurological symptoms are present at the time of diagnosis of SLE but also with complications that occurred after diagnosis. In the presented case, the appearance of flaccid tetraparesis with areflexia suggested peripheral damage to the nervous system. In the electromyography performed in this patient, acute axonal polyneuropathy was mainly suspected. Further differential diagnosis should consider other acute and subacute developing polyneuropathies. Guillain-Barré polyneuropathy deserves special attention. To our knowledge, this is the first case documented in the literature of the coexistence of critical illness polyneuropathy and SLE.