Neonatal treatment with tamoxifen causes immediate alterations of the sexually dimorphic nucleus of the preoptic area and medial preoptic area in male rats

We have characterized two different types of Cl- currents in calf pulmonary artery endothelial (CPAE) cells by using a combined patch-clamp and Fura-2 microfluorescence technique to measure simultaneously ionic currents and the intracellular Ca2+ concentration, Ca2+]i. Exposure of CPAE cells to 28% hypotonic solution induces cell swelling without a change in membrane capacitance and Ca2+]i, and concomitantly activates a current. This current, I(Cl, vol), is closely correlated with the changes in cell volume and shows a modest outward rectification. It slowly inactivates at potentials more positive than +60 mV but is time- and voltage-independent at other potentials. Increase in Ca2+]i by different maneuvers, such as application of vasoactive agonists (ATP), ionomycin, or loading of the cells directly with Ca2+ also activates a Cl- current, I(Cl, Ca). This current slowly activates at positive potentials, inactivates quickly at negative potentials and shows strong outward rectification. A time-independent component of the current activated by elevation of Ca2+]i alone can be inhibited by cell shrinking by exposing the cells to hypertonic solution, indicating that an increase in Ca2+]i also co-activates I(Cl, vol). Forskolin or cAMP never activated a current in CPAE cells, which indicates the lack of cAMP-activated channels in these cells. There is also no evidence for the existence of voltage-gated Cl- channels in resting, nonstimulated cells. Challenging a cell with elevated Ca2+]i and hypotonic solutions activated I(Cl, vol) on top of I(Cl, Ca), suggesting that I(Cl, Ca) and I(Cl, vol) are different channels. We conclude that CPAE cells do not express voltage-gated (ClC-type) or cAMP-gated (CFTR-type) Cl- channels, but activate large Cl- currents after volume (mechanical?) or chemical (Ca2+) stimulation.