GABA can evoke norepinephrine (NE) release by activating GABAA receptors or GABA transporters on noradrenergic terminals. The heterocarrier-induced release occurs by conventional exocytosis. We here characterized the mechanism of the GABAA receptor-induced release and investigated what type(s) of voltage-sensitive Ca2+ channels (VSCCs) are involved in the GABA heterocarrier and GABA(A) receptor-evoked release. The effect of GABA in superfused rat hippocampal synaptosomes prelabeled with [(3)H]-NE was partially prevented by bicuculline or the GABA uptake inhibitor SKF 89976A and abolished by blocking both GABAA receptors and GABA transporters. The release elicited through GABAA receptors was Ca2+-dependent, prevented by Cd2+ or by botulinum toxin C, and modulated through alpha2 autoreceptors. The GABAA receptor-evoked release was insensitive to nifedipine and to omega-conotoxin MVIIC, but was inhibited ( approximately 50%) by omega-conotoxin GVIA. The heterocarrier-evoked release, nifedipine-insensitive, was inhibited approximately 30% either by omega-conotoxin GVIA or by omega-conotoxin MVIIC; the combined toxins produced approximately 60% inhibition. To conclude: a) the releases of NE evoked by activation of GABA(A) receptors and GABA heterocarriers are additive, although they both occur by conventional exocytosis; b) the heterocarrier-induced release requires activation of N and P/Q type channels, whereas the GABAA receptor-induced release only involves channels of the N type.

2082 hypercholesterolemic subjects were treated with simvastatin for 12 weeks. In 530 patients the dose was increased after 6 weeks from 10 to 20 mg because of persistently high cholesterol concentrations. Total cholesterol (TC) in the 1552 patients taking 10 mg fell by 1.61 mmol.l-1 (18.4%), LDL cholesterol (LDLC) by 1.53 mmol.l-1 (25.2%), and triglycerides (TG) by 0.13 mmol.l-1 (5.5%); HDL cholesterol (HDLC) significantly increased by 0.05 mmol.l-1 (3.6%). In the 530 patients taking 20 mg TC fell by 1.89 mmol.l-1 (19.9%), LDLC by 1.78 mmol.l-1 (26.0%), and TG by 0.13 mmol.l-1 (5.5%); HDLC increased by 0.05 mmol.l-1 (3.7%). The reductions in TC, LDLC, and TG were positively correlated and the increase in HDLC negatively correlated with their respective baseline values. There were independent significant correlations of the fall in LDLC with sex (MANOVA), baseline TG, and adherence to a lipid-lowering diet. The falls in TG significantly correlated with baseline fructosamine concentrations and dietary adherence. There were 571 adverse events in 16.6% of the patients but no case of myopathy. These results show that simvastatin is usually well tolerated and that its effects on TC and LDLC depend on their baseline concentrations.

Plasma concentrations of pirprofen and of its pyrrol metabolite were assessed in 9 elderly patients (3 males, 6 females; mean age 76 years) suffering from chronic degenerative disease. Pirprofen 400 mg in 4 ml was administered i.m. and the pharmacokinetic profile of the drug and the metabolite was calculated. The AUC, Cmax and t1/2 of pirprofen were similar to those found in previous studies, and, as expected, those parameters for the pyrrol metabolite were lower (Cmax = 2.8 micrograms/ml-1; tmax = 6.4 h; AUC(0-32) = 56.5 micrograms.h.ml-1). One patient (n = 8) showed different pharmacokinetic behaviour, which is discussed. The data suggest that age has little influence on the pharmacokinetic of pirprofen, although unpredictable responses should always be considered in clinical practice.