Parkinson's disease (PD) is the second most prevalent age-related neurodegenerative disease with physiological manifestations including tremors, bradykinesia, abnormal postural reflexes, rigidity and akinesia and pathological landmarks showing losses of dopaminergic neurons in the substantia nigra. Although the etiology of PD has been intensively pursued for several decades, biochemical mechanisms and genetic and epigenetic factors leading to initiation and progression of the disease remain elusive. Environmental toxins including (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) MPTP, paraquat and rotenone have been shown to increase the risk of PD in humans. Oxidative stress remains the leading theory for explaining progression of PD. Studies with cell and animal models reveal oxidative and inflammatory properties of these toxins and their ability to activate glial cells which subsequently destroy neighboring dopaminergic neurons. This review describes pathological effects of neurotoxins on cells and signaling pathways for production of reactive oxygen species (ROS) that underline the pathophysiology of PD.

A rapid, easy, and accurate method for converting the fluorescence of BCECF to pH, as an alternative to the nigericin method, is described. The ratio of the fluorescence intensities for BCECF can be converted to pH between 4 and 9 by a formula similar to the one used to calculate [Ca2+]i from the fluorescence of fura2. The formula is inverted because H+ binding to BCECF causes a decrease in fluorescence, whereas Ca2+ binding to fura2 causes an increase in fluorescence. The ratio of the fluorescence intensities is a sigmoidal function of the [H+] between pH 4 and 9 with an essentially linear mid region from pH 6 to 8. This calibration procedure in cells is similar to the popular method for fura2 where ionomycin, Ca2+, and an alkaline EGTA solution are added in succession to change the intracellular pCa from 4 to 9. For BCECF in cells, a protonophore, FCCP or CCCP, is added and the cells are titrated with acid to an intracellular pH of 4 and then back to pH 9 with base by observing the gradual change in fluorescence as it asymptotically reaches its limiting minimum and maximum values. This method does not require changing the medium to one with high KCl to depolarize the membrane potential nor does the proton concentration need to be equilibrated across the plasma membrane. The technique can be used to calibrate BCECF in sheets of cells, as well as suspensions of cells over a wide range of pH sensitivities.

The interaction of cardiac Na+-Ca2+ exchange (NCX1) with caveolin proteins was investigated in sarcolemmal vesicles. Western blots of sarcolemmal vesicles revealed the presence of caveolin-1, -2, and -3. NCX1 co-fractionated more closely with caveolin-3 than caveolin-1 on sucrose density gradients. NCX1 has five possible caveolin-binding motifs and NCX1 co-precipitated specifically with caveolin-3. Molecular sieve column chromatography indicated that this co-precipitation was not due to incomplete solubilization of lipid raft microdomains. Cholesterol chelation in vesicles decreased NCX1 transport activity and caveolin-3 co-precipitation. NCX1 may play a role in caveolar transmembrane signaling in addition to its role in excitation-contraction coupling.

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The cardiac Na/Ca exchanger's (NCX1) role in calcium homeostasis during myocardial contractility makes it a possible target of signaling factors regulating inotropy. Caveolae, structured invaginations of the plasmalemma, are known to concentrate a wide variety of signaling factors. The predominant coat proteins of caveolae, caveolins, dock to and regulate the activity of these signaling factors and other proteins through interaction with their scaffolding domain. In this study we investigated the interaction of NCX1 with caveolin proteins. Western blots of bovine cardiac sarcolemmal vesicles revealed the presence of caveolin‐1, ‐2, and ‐3. Immunoprecipitation of detergent‐solubilized vesicle proteins with either NCX1 or caveolin‐3 antibodies indicated that NCX1 coprecipitates with caveolin‐3, but not with caveolin‐1 and ‐2. Functional disruption of caveolae, by β‐cyclodextrin treatment of vesicles, diminished coprecipitation of caveolin‐3 and NCX1 activity. NCX1 has five potential caveolin‐binding motifs, two of which are in the transporter's exchange inhibitory peptide (XIP) domain. The presence of 50 mM XIP peptide enhanced coprecipitation of caveolin‐3 with NCX1 independent of calcium concentration. We conclude that NCX1 associates specifically with caveolin‐3. Partitioning of NCX1 in caveolae has implications for temporal and spatial regulation of excitation‐contraction and ‐relaxation coupling in cardiac myocytes.