Ligands that selectively inhibit human a3b2 and a6b2 nicotinic acetylcholine receptor (nAChRs) and not the closely related a3b4 and a6b4 subtypes are lacking. Current a-conotoxins (a-Ctxs) that discriminate among these nAChR subtypes in rat fail to discriminate among the human receptor homologs. In this study, we describe the development of a-Ctx LvIA(N9R,V10A) that is 3000-fold more potent on oocyte-expressed human a3b2 than a3b4 and 165-fold more potent on human a6/a3b2b3 than a6/ a3b4 nAChRs. This analog was used in conjuction with three other a-Ctx analogs and patch-clamp electrophysiology to characterize the nAChR subtypes expressed by human adrenal chromaffin cells. LvIA(N9R,V10A) showed little effect on the acetylcholine-evoked currents in these cells at concentrations expected to inhibit nAChRs with b2 ligand-binding sites. In contrast, the b4-selective a-Ctx BuIA(T5A,P6O) inhibited .98% of the acetylcholine-evoked current, indicating that most of the heteromeric receptors contained b4 ligand-binding sites. Additional studies using the a6-selective a-Ctx PeIA(A7V,S9H,V10A, N11R,E14A) indicated that the predominant heteromeric nAChR expressed by human adrenal chromaffin cells is the a3b4* subtype (asterisk indicates the possible presence of additional subunits). This conclusion was supported by polymerase chain reaction experiments of human adrenal medulla gland and of cultured human adrenal chromaffin cells that demonstrated prominent expression of RNAs for a3, a5, a7, b2, and b4 subunits and a low abundance of RNAs for a2, a4, a6, and a10 subunits.

DACD is an adequate source of organs for kidney transplantation. Our functional and survival results are encouraged in the short term, although further work is required to increase the program's benefits.

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Varenicline is a nicotinic acetylcholine receptor (nAChR) agonist used to treat nicotine addiction but a live debate persists concerning its mechanism of action in reducing nicotine consumption. Although initially reported as α4β2-selective, varenicline was subsequently shown to activate other nAChR subtypes implicated in nicotine addiction including α3β4. However, it remains unclear whether activation of α3β4 nAChRs by therapeutically relevant concentrations of varenicline is sufficient to affect the behavior of cells that express this subtype. We used patch-clamp electrophysiology to assess the effects of varenicline on native α3β4* nAChRs (asterisk denotes the possible presence of other subunits) expressed in human adrenal chromaffin cells and compared its effects to those of nicotine. Varenicline and nicotine activated α3β4* nAChRs with EC50 values of 1.8 (1.2-2.7) μM and 19.4 (11.1-33.9) μM, respectively. Stimulation of adrenal chromaffin cells with 10 ms pulses of 300 μM acetylcholine (ACh) in current-clamp mode evoked sodium channel-dependent action potentials (APs). Under these conditions, perfusion of 50 nM or 100 nM varenicline showed very little effect on AP firing compared to control conditions (ACh stimulation alone) but at higher concentrations (250 nM) varenicline increased the number of APs fired up to 436 ± 150%. These results demonstrate that therapeutic concentrations of varenicline are unlikely to alter AP firing in chromaffin cells. In contrast, nicotine showed no effect on AP firing at any of the concentrations tested (50, 100, 250, and 500 nM). However, perfusion of 50 nM nicotine simultaneously with 100 nM varenicline increased AP firing by 290 ± 104% indicating that exposure to varenicline and nicotine concurrently may alter cellular behavior including excitability and neurotransmitter release.

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In the recent years, more than 60% of available deceased donors are either older than 50 yr or have significant vascular comorbidities. This makes the acceptance and rejection criteria of renal allografts very rigorous, especially in cases of younger recipients, and at the same time encourages live donations. In our country, there is a lack of homogeneity in the percentages of use of expanded criteria donor (ECD) allografts between the different autonomous communities. Furthermore, the criteria vary greatly, and in some cases, great importance is given to the biopsy while in others very little. In this study, we present a unified and homogenous criteria agreed upon by consensus of a 10-member Panel representing major scientific societies related to renal transplantation in Spain. The criteria are to be used in accepting and/or rejecting kidneys from the so-called ECDs. The goal was to standardize the use of these organs, to optimize the results, and most importantly to provide for the maximum well being of our patients. Finally, we believe that after taking into account the Panel's thorough review of specific scientific literature, this document will be adaptable to other national renal transplant programmes.

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