Correlation of open cell-attached and excised patch clamp techniques

The excised patch clamp configuration provides a unique technique for some types of single channel analyses, but maintenance of stable, long-lasting preparations may be confounded by rundown and/or rapid loss of seal. Studies were performed on the amiloride-sensitive Na⁺ channel, located on the apical surface of A₆ cells, to determine whether the nystatininduced open cell-attached patch could serve as an alternative configuration.Compared to excised inside-out patches, stable preparations were achieved more readily with the open cell-attached patch (9% vs. 56% of attempts). In both preparations, the current voltage (I-V) relation was linear, current amplitudes were equal at opposite equivalent clamped voltages, and E _rev was zero in symmetrical Na⁺ solutions, indicating similar Na⁺ activities on the cytosolic and external surfaces of the patch. Moreover, there was no evidence that nystatin altered channel activity in the patch because slope conductance (3–4pS) and E _rev (75 mV), when the bath was perfused with a high K:low Na solution (E _Na=80 mV), were nearly equal in both patch configurations.Our results therefore indicate that the nystatininduced open cell-attached patch can serve as an alternative approach to the excised inside-out patch when experiments require modulation of univalent ions in the cytosol.We thank Dr. Olaf S. Andersen for his suggestions in the development of the open cell-attached recording technique. This work was supported by a National Institutes of Health grant (DK-18061)     

A new role for PGRP-S (Tag7) in immune defense: lymphocyte migration is induced by a chemoattractant complex of Tag7 with Mts1

PGRP-S (Tag7) is an innate immunity protein involved in the antimicrobial defense systems, both in insects and in mammals. We have previously shown that Tag7 specifically interacts with several proteins, including Hsp70 and the calcium binding protein S100A4 (Mts1), providing a number of novel cellular functions. Here we show that Tag7–Mts1 complex causes chemotactic migration of lymphocytes, with NK cells being a preferred target. Cells of either innate immunity (neutrophils and monocytes) or acquired immunity (CD4⁺ and CD8⁺ lymphocytes) can produce this complex, which confirms the close connection between components of the 2 branches of immune response.     

The Ca2+ channel β2 subunit is selectively targeted to the axon terminals of supraoptic neurons

The assembly of high voltage-activated Ca²⁺ channels with different β subunits influences channel properties and possibly subcellular targeting. We studied β subunit expression in the somata and axon terminals of the magnocellular neurosecretory cells, which are located in the supraoptic nucleus (SON) and neurohypophysis, respectively. Antibodies directed against the 4 Ca_Vβ subunits (Ca_Vβ₁-Ca_Vβ₄) were used for immunoblots and for immunostaining of slices of these two tissues. We found that all 4 β subunits are expressed in both locations, but that Ca_Vβ₂ had the highest relative expression in the neurohypophysis. These data suggest that the Ca_Vβ₂ subunit is selectively targeted to axon terminals and may play a role in targeting and/or regulating the properties of Ca²⁺ channels.     

Adaptation to salinity at the plant cell level

Summary Various mechanisms of adaptation of plant cells to salinity are reviewed: (1) protection of enzymes and maintenance of turgor by organic solutes; (2) prevention of ion toxicity by compartmentation; and (3) energization of solute transport by the proton pump. All these mechanisms seem to play a role in adaptation. The particular advantages of using salt-adapted cells in suspension culture to identify mechanisms of adaptation are pointed out.     

Ethanol Administration in the Rat Decreases Prostacyclin Production by Isolated Brain Microvessels

The effects of short- and long-term ethanol administration to rats on basal levels and formation of prostacyclin (PGI2) measured as 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), and on lipid class content and fatty acid composition of isolated brain microvessels (BMV) were studied. After acute treatment (2 h, at the peak of plasma ethanol concentration) basal 6-keto-PGF1 alpha levels in BMV and release on incubation were reduced to 50% of control values. After chronic administration (15 days), PGI2 release was reduced to about 40% of control values, without changes in basal levels. Total lipid, phospholipid, and cholesterol levels in BMV, measured after prolonged administration of alcohol, were not modified. Also, only minor changes in the fatty acid composition of individual phospholipid classes were detected. The observed reduction of PGI2 synthesis in BMV thus could not be related to changes of the fatty acid precursor pool in the preparation. Precursor release and/or the biosynthetic pathways may be affected by ethanol administration.