Recovery from hypoxia-induced internalization of cardiac Na+ /H + exchanger 1 requires an adequate intracellular store of antioxidants.

The heart is highly active metabolically but relatively underperfused and, therefore, vulnerable to ischemia. In addition to acidosis, a key component of ischemia is hypoxia that can modulate gene expression and protein function as part of an adaptive or even maladaptive response. Here, using cardiac-derived HL-1 cells, we investigate the effect of various hypoxic stimuli on the expression and activity of Na+ /H + exchanger 1 (NHE1), a principal regulator of intracellular pH. Acute (10 min) anoxia produced a reversible decrease in the sarcolemmal NHE1 activity attributable to NHE1 internalization. Treatment with either 1% O 2 or dimethyloxaloylglycine (DMOG; 1 mM) for 48-hr stabilized hypoxia-inducible factor 1 and reduced the sarcolemmal NHE1 activity by internalization, but without a change in total NHE1 immunoreactivity or message levels of the coding gene ( SLC9A1) determined in whole-cell lysates. Unlike the effect of DMOG, which was rapidly reversed on washout, reoxygenation after a prolonged period of hypoxia did not reverse the effects on NHE1, unless media were also supplemented with a membrane-permeant derivative of glutathione (GSH). Without a prior hypoxic episode, GSH supplementation had no effect on the NHE1 activity. Thus, posthypoxic NHE1 reinsertion can only take place if cells have a sufficient reservoir of a reducing agent. We propose that oxidative stress under prolonged hypoxia depletes intracellular GSH to an extent that curtails NHE1 reinsertion once the hypoxic stimulus is withdrawn. This effect may be cardioprotective, as rapid postischaemic restoration of the NHE1 activity is known to trigger reperfusion injury by producing an intracellular Na + -overload, which is proarrhythmogenic.

Synthesis and studies on antidepressant and anticonvulsant activities of some 3-(2-thienyl)pyrazoline derivatives.

In this study, the synthesis of twelve 3-(2-thienyl)pyrazoline derivatives are described. The structures of all compounds were confirmed by UV, IR, (1)H-NMR, mass spectral data, and microanalyses. In the pharmacological studies, antidepressant and anticonvulsant activities of these compounds have been screened. The antidepressant activities of the compounds were investigated by Porsolt's behavioral despair test (forced swimming) on albino mice and compared with tranylcypromine. Among the compounds examined, the compounds 9 and 12 showed significant antidepressant activity. Anticonvulsant activities of the compounds were determined by maximal electroshock seizure (MES) and subcutaneous pentylenetetrazole (metrazol) (scMet.) tests, neurotoxicities were determined by rotarod toxicity test on albino mice. Compound 8 was found to be protective against MES in the range of 30-300 mg/kg dose levels at four hours. None of the synthesized compounds showed neurotoxicity at 30-300 mg/kg dose levels.