Background-Hypertensive patients with renovascular disease (RVD) may be exposed to increased oxidative stress, possibly related to activation of the renin-angiotensin system. Methods and Results-We measured the urinary excretion of 8-iso-prostaglandin (PG) F 2␣ and 11-dehydro-thromboxane (TX) B 2 as indexes of in vivo lipid peroxidation and platelet activation, respectively, in 25 patients with RVD, 25 patients with essential hypertension, and 25 healthy subjects. Plasma renin activity in peripheral and renal veins, angiotensin II in renal veins, cholesterol, glucose, triglycerides, homocysteine, and antioxidant vitamins A, C, and E were also determined. Patients were also studied 6 months after a technically successful angioplasty of the stenotic renal arteries. Urinary 8-iso-PGF 2␣ was significantly higher in patients with RVD (median, 305 pg/mg creatinine; range, 124 to 1224 pg/mg creatinine) than in patients with essential hypertension (median, 176 pg/mg creatinine; range, 48 to 384 pg/mg creatinine) or in healthy subjects (median, 123 pg/mg creatinine; range, 58 to 385 pg/mg creatinine). Urinary 11-dehydro-TXB 2 was also significantly higher in RVD patients compared with healthy subjects. In RVD patients, urinary 8-iso-PGF 2␣ correlated with 11-dehydro-TXB 2 (r s ϭ0.

1. The activities of the ethoxycoumarin O-deethylase (ECOD), epoxide hydrolase (EH), UDP-glucuronyl transferase (GT), glutathione S-transferase (GST), acetyl transferase (AT) and sulphotransferase (ST) were measured in 6 liver, 8 lung, 8 kidney, 8 intestinal mucosa and 22 urinary bladder mucosa specimens from human subjects. EH and GT were studied with styrene oxide and 1-naphthol, respectively, as substrates, GST, AT and ST were studied with benzo(a)pyrene-4,5-oxide, p-aminobenzoic acid and 2-naphthol, respectively. 2. The enzyme activities were detectable at significant rates in liver, lungs, kidneys and gut. In urinary bladder, EH, GT, GST and ST only were detectable. The liver catalyzed the various reactions at higher rates than did other tissues. 3. Of the extrahepatic tissues, the intestinal mucosa contained the highest activities of AT (50% of liver) and ST (30% of liver), whereas kidneys contained the highest activity of GT (50% of liver) and GST (80% of liver). GST was the enzyme with the widest tissue distribution.

The effects of percutaneous transluminal renal angioplasty (PTRA) on the renal function of stenotic kidneys are usually assessed by evaluating the changes in serum creatinine, which is quite a rough indicator of glomerular filtration rate (GFR). In 27 hypertensive patients with 19 atherosclerotic and 11 fibromuscular significant renal artery stenoses, we investigated with renal scintigraphy the short-term (5 days) and long-term (10 months) effects of a technically successful PTRA (in seven cases combined with a stent implantation) on GFR of the stenotic and contralateral kidneys; these measurements were combined with those of plasma renin activity (PRA) and of angiotensin II (AII). We found that in short-term studies after PTRA GFR rose from 29.7 +/- 3.5 to 34.6 +/- 3.1 mL/min and from 36.9 +/- 4.0 to 45.1 +/- 4.3 mL/min, respectively, in atherosclerotic and fibromuscular poststenotic kidneys. In long-term studies GFR further and significantly increased, to 37.8 +/- 3.2 mL/min in the former group, whereas it stabilized in the latter group (46.0 +/- 3.6 mL/min). In patients with fibromuscular stenosis these changes in GFR were associated with clear-cut reductions in blood pressure (BP), PRA, and AII; these decrements also occurred in patients with atherosclerotic stenosis but to a much lesser extent. We also found that in short- and long-term studies the percent of PTRA-induced increments of GFR in the poststenotic kidneys were inversely correlated with the baseline values of GFR. In addition, the absolute and percent increments of GFR were positively correlated with the basal levels of AII. Thus the time course of the improvement in GFR after angioplasty may differ in kidneys, depending on the etiology of the stenosis, in that in those with fibromuscular stenosis it was entirely apparent within a few days whereas in those with atherosclerotic stenosis it required several months to be fully expressed. Also, it appears that the more compromised kidneys are those that benefit most from the dilatation and that AII levels are useful indicators of the possibility that the stenotic kidney will have a favorable functional outcome in terms of restoration of renal blood flow.

Sphingosine 1-phosphate (S1P) activates a subset of plasma membrane receptors of the endothelial differentiation gene family (EdgRs) in many cell types. In C2C12 myoblasts, exogenous S1P elicits Ca2+ transients by activating voltage-independent plasma membrane Ca2+ channels and intracellular Ca2+-release channels. In this study, we investigated the effects of exogenous S1P on voltage-dependent L-type Ca2+ channels in skeletal muscle fibers from adult mice. To this end, intramembrane charge movements (ICM) and L-type Ca2+ current (I(Ca)) were measured in single cut fibers using the double Vaseline-gap technique. Our data showed that submicromolar concentrations of S1P (100 nM) caused a approximately 10-mV negative shift of the voltage threshold and transition voltages of q(gamma) and q(h) components of ICM, and of I(Ca) activation and inactivation. Biochemical studies showed that EdgRs are expressed in skeletal muscles. The involvement of EdgRs in the above S1P effects was tested with suramin, a specific inhibitor of Edg-3Rs. Suramin (200 microM) significantly reduced, by approximately 90%, the effects of S1P on ICM and I(Ca), suggesting that most of S1P action occurred via Edg-3Rs. Moreover, SIP at concentration above 10 microM elicited intracellular Ca2+ transients in muscle fibers loaded with the fluorescent Ca2+ dye Fluo-3, as detected by confocal laser scanning microscopy.

Although deep brain stimulation (DBS) is a clinically effective therapy for patients with advanced Parkinson's disease (PD), its physiological effects on the brain and possible actions on non-motor functional systems remain largely unknown. This study evaluated the effects of DBS of the subthalamic nucleus (STN) on neurophysiological variables and on cardiovascular physiology. Nine patients affected by PD undergoing chronic DBS of the STN have been studied. We performed electroencephalography (EEG), somatosensory (SEPs) and visual evoked potentials (VEPs), exteroceptive masseteric silent period and sympathetic skin response (SSR) studies with DBS ON and OFF. To assess the effects of stimulation on the cardiovascular system the tilt test and plasma renin activity were studied. When we turned the DBS OFF, both SEP N20 and the VEP P100 component increased significantly in amplitude whereas the SSR decreased in amplitude and increased in latency. Although plasma renin activity tended to increase with DBS OFF, its modification induced by postural changes and blood pressure values did not significantly differ with DBS ON and OFF. We conclude that DBS of the STN in PD, besides inducing a clinical improvement, induces several non-motor effects.

Intramembrane charge movements, IICM, were measured in rat skeletal muscle fibres in response to voltage steps from a −90 mV holding potential to a wide test voltage range (−85 to 30 mV), using a double Vaseline‐gap voltage‐clamp technique. Solutions were designed to minimise ionic currents. Ca2+ current was blocked by adding Cd2+ (0.8 mm) to the external solution. In a subset of experiments Cd2+ was omitted to determine which components of the charge movement best correlated with L‐type Ca2+ channel gating. Detailed kinetic analysis of IICM identified two major groups of charges. The first two components, designated Qa and Qb, were the only charges moved by small depolarising steps. The second group of components, Qc and Qd, showed a more positive voltage threshold, −35.6 ± 2.0 mV, (n= 6) in external solution with Cd2+, and −41.1 ± 2.0 mV (n= 12) in external solution without Cd2+. Notably, in external solution without Cd2+ the voltage threshold of Ca2+ current, ICa, activation had a similar value, being −38.1 ± 2.4 mV. The sum of three Boltzmann functions, Q1, Q2 and Q3, showing progressively more positive transition voltages, could be fitted to charge versus voltage, QICM‐V, plots. The three Boltzmann terms identified three charge components: Q1 described the shallow voltage‐dependent Qa and Qb charges, Q2 and Q3 described the steep voltage‐dependent Qc and Qd charges. In external solution without Cd2+ the charge kinetics changed: a slow decaying phase was replaced by a pronounced delayed hump. Moreover, the transition voltages of the individual steady‐state charge components were shifted towards negative potentials (from 6.3 to 8.2 mV). Nevertheless, the overall charge and steepness factors were conserved. In conclusion, these experiments allowed a clear separation of four components of intramembrane charge movements in rat skeletal muscle, showing that there are no fundamental differences with respect to charge movement components between amphibian and mammalian twitch muscle. Moreover, Qc and Qd charge are correlated with L‐type Ca2+ channel gating.

1. The activation of the L-type calcium current (ICa) was studied in normally polarized (-100 mV) cut skeletal muscle fibres of the frog with the double Vaseline-gap voltage-clamp technique. Both external and internal solutions were Ca2P buffered. Solutions were made in order to minimize all but the Ca2P current.2. The voltage-dependent components of the time course of activation were determined by two procedures: fast and slow components were evaluated by multiexponential fitting to current traces elicited by long voltage pulses (5 s) after removing inactivation; fast components were also determined by short voltage pulses having different duration (0 5-70 ms). 3. The components of deactivation were evaluated after removing the charge-movement current from the total tail current by the difference between two short (50 and 70 ms) voltage pulses to 10 mV, moving the same intramembrane charge. Two exponential components, fast and slow (time constants, 6 + 0 3 and 90 + 7 ms at -100 mV; n = 26), were found. 4. The time onset of ICa was evaluated either by multiexponential fitting to the ICa activation or by pulses of different duration to test the beginning of the 'on' and 'off' inequality. This was at about 2 ms, denoting that it was very early. 5. The time constants vs. voltage plots indicated the presence of four voltage-dependent components in the activation pathway. Various kinetic models are discussed. Models with independent transitions, like a Hodgkin-Huxley scheme, were excluded. Suitable models were a five-state sequential and a four-state cyclic with a branch scheme. The latter gave the best simulation of the data. 6. The steady-state activation curve saturated at high potentials. It had a half-voltage value of 1 + 0-02 mV and the opening probability was only 0-82 + 0-2 at 20 mV (n = 32). This result implies a larger number of functional calcium channels than was previously supposed and is in agreement with the number of dihydropyridine (DHP) receptors calculated for the tubular system.

The dihydropyridine receptors (DHPRs)/L-type Ca 2+ channels of skeletal muscle are coupled with ryanodine receptors/Ca 2+ release channels (RyRs/CRCs) located in the sarcoplasmic reticulum (SR). The DHPR is the voltage sensor for excitation-contraction (EC) coupling and the charge movement component q γ has been implicated as the signal linking DHPR voltage sensing to Ca 2+ release from the coupled RyR. Recently, a new charge component, q h , has been described and related to L-type Ca 2+ channel gating. Evidence has also been provided that the coupled RyR/CRC can modulate DHPR functions via a retrograde signal. Our aim was to investigate whether the newly described q h is also involved in the reciprocal interaction or cross-talk between DHPR/L-type Ca 2+ channel and RyR/CRC. To this end we interfered with DHPR/L-type Ca 2+ channel function using nifedipine and 1-alkanols (heptanol and octanol), and with RyR/CRC function using ryanodine and ruthenium red (RR). Intramembrane charge movement (ICM) and L-type Ca 2+ current (I Ca ) were measured in single cut fibres of the frog using the double-Vaseline-gap technique. Our records showed that nifedipine reduced the amount of q γ and q h moved by ∼90% and ∼55%, respectively, whereas 1-alkanols completely abolished them. Ryanodine and RR shifted the transition voltages of q γ and q h and of the maximal conductance of I Ca by ∼4−9 mV towards positive potentials. All these interventions spared q β . These results support the hypothesis that only q γ; and q h arise from the movement of charged particles within the DHPR/L-type Ca 2+ channel and that these charge components together with I Ca are affected by a retrograde signal from RyR/CRC.