No abstract

The features of Ca 2+ fluxes, the importance of the Ca 2+ pump-mediated H + /Ca 2+ exchanges at plasmalemma level, and the possible involvement of Ca 2+ -ATPase activity in ABA-induced changes of H + fluxes were studied in Egeria densa leaves. The results presented show that, while in basal conditions no net Ca 2+ flux was evident, a conspicuous Ca 2+ influx (about 1.1 µmol g -1 FW h -1 ) occurred. The concomitant efflux of Ca 2+ was markedly reduced by treatment with 5 µM eosin Y (EY), a specific inhibitor of the Ca 2+ -ATPase, that completely blocked the transport of Ca 2+ after the first 20 -30 min. The decrease in Ca 2+ efflux induced by EY was associated with a significant increase in net H + extrusion (-∆H + ) and a small but significant cytoplasmic alkalinization. The shift of external [Ca 2+ ] from 0.3 to 0.2 mM (reducing Ca 2+ uptake by about 30 %) and the hindrance of Ca 2+ influx by La 3+ were accompanied by progressively higher -∆H + increases, in agreement with a gradual decrease in the activity of a mechanism counteracting the Ca 2+ influx by an nH + /Ca 2+ exchange. The ABA-induced decreases in -∆H + and pH cyt were accompanied by a significant increase in Ca 2+ efflux, all these effects being almost completely suppressed by EY, in line with the view that the ABA effects on H + fluxes are due to activation of the plasmalemma Ca 2+ -ATPase. These results substantially stress the high sensitivity and efficacy of the plasmalemma Ca 2+ pump in removing from the cytoplasm the Ca 2+ taken up, and the importance of the contribution of Ca 2+ pump-mediated H + /Ca 2+ fluxes in bringing about global changes of H + fluxes at plasmalemma level.

No abstract

Wearing-off refers to the predictable worsening of motor and sometimes non-motor symptoms of Parkinson's disease occurring at the end of levodopa dose that improves with the next drug dose. Here, we investigated the efficacy of rasagiline on executive functions at the end of levodopa dose in patients displaying symptoms of wearing-off. Rasagiline was well-tolerated and produced a significant improvement at the Frontal Assessment Battery, together with improvement of motor symptoms at the end of levodopa dose. These results suggest that treatment of motor symptoms of wearing-off with rasagiline may be accompanied by improvement of executive functions, and further support the need for optimizing dopamine replacement therapy in fluctuating Parkinson's disease patients.

Orthostatic hypotension is a frequent non-motor symptom of Parkinson's disease, with negative prognostic role on cognitive functions. Here we measured the acute effects of orthostatic hypotension on executive functions in Parkinson's disease patients devoid of hypertension, carotid artery stenosis, and significant chronic cerebrovascular pathology. Measurements were carried out during regular visits in outpatient setting. Twenty-eight Parkinson's disease patients were recruited and studied along scheduled outpatient visits. They were divided into two groups (n = 14 each) based on the presence or lack of orthostatic hypotension. This was diagnosed according to international guidelines. All patients were submitted to the Stroop's test and to the phonological and semantic verbal fluency test after 10-min resting in supine position and immediately upon standing in upright position. Testing lasted less than 5 min in either position. In upright position, subjects with orthostatic hypotension displayed significantly worse performances at the Stroop's test word reading time (22.1 ± 4.1 vs. 14.9 ± 4.0 s), interference time (56.1 ± 12.3 vs. 41.4 ± 11.8 s), and number of errors at the interference section (5.8 ± 3.2 vs. 1.3 ± 2.1) as compared to those without orthostatic hypotension. These results demonstrate that worsening of attentive function upon standing can be measured in Parkinson's disease patients with orthostatic hypotension during routine outpatient visits. These findings suggest that clinically asymptomatic orthostatic hypotension in Parkinson's disease patients may acutely worsen neuropsychological performances with possible negative impact on daily functioning.