Synthesis and hydrolysis of ATP by intact chloroplasts under flash illumination and in darkness

ATP concentrations were measured in isolated intact spinach chloroplasts under various light and dark conditions. The following results were obtained: (1) Even in darkened chloroplasts and in the absence of exogenous substrates, ATP levels in the chloroplast stroma were significant. They decreased on addition of glycerate, phosphoglycerate or dihydroxyacetone phosphate. When dihydroxyacetone phosphate and oxaloacetate were added together, ATP levels increased in darkened chloroplasts owing to substrate level phosphorylation. (2) Under illumination with saturating single turnover flashes, oxygen evolution in the presence of phosphoglycerate, whose reduction requires ATP, was no lower on a unit flash basis at the low flash frequency of 2 Hz than at higher frequencies. Quenching of 9-aminoacridine fluorescence, which indicates the formation of a proton gradient in intact chloroplasts, decreased with decreasing flash frequencies, until there was no significant fluorescence quenching at a flash frequency of about 2 Hz. In contrast to intact chloroplasts, broken chloroplasts did not phosphorylate much ADP at the low flash frequency of 2 Hz. (3) Flashing at extremely low frequencies (0.2 Hz) caused ATP hydrolysis rather than ATP synthesis in intact chloroplasts. At higher flash frequencies, synthesis replaced hydrolysis. Still, even at high frequencies (10 Hz), the first flashes of a series of flashes given after a long dark time always decreased chloroplast ATP levels.From these results, it is concluded that the enzyme, which mediates ATP synthesis in the light, is inactive in darkened intact chloroplasts. Its light activation can be separated from the formation of the high energy condition, which results in ATP synthesis. After its activation, the enzyme catalyzes a reversible reaction.     

Synthesis and hydrolysis of ATP by intact chloroplasts under flash illumination and in darkness.

ATP concentrations were measured in isolated intact spinach chloroplasts under various light and dark conditions. The following results were obtained: (1) Even in darkened chloroplasts and in the absence of exogenous substrates, ATP levels in the chloroplast stroma were significant. They decreased on addition of glycerate, phosphoglycerate or dihydroxyacetone phosphate. When dihydroxyacetone phosphate and oxaloacetate were added together, ATP levels increased in darkened chloroplasts owing to substrate level phosphorylation. (2) Under illumination with saturating single turnover flashes, oxygen evolution in the presence of phosphoglycerate, whose reduction requires ATP, was no lower on a unit flash basis at the low flash frequency of 2 Hz than at higher frequencies. Quenching of 9-aminoacridine fluorescence, which indicates the formation of a proton gradient in intact chloroplasts, decreased with decreasing flash frequencies, until there was no significant fluorescence quenching at a flash frequency of about 2 Hz. In contrast to intact chloroplasts, broken chloroplasts did not phosphorylate much ADP at the low flash frequency of 2 Hz. (3) Flashing at extremely low frequencies (0.2 Hz) caused ATP hydrolysis rather than ATP synthesis in intact chloroplasts. At higher flash frequencies, synthesis replaced hydrolysis. Still, even at high frequencies (10 Hz), the first flashes of a series of flashes given after a long dark time always decreased chloroplast ATP levels. From these results, it is concluded that the enzyme, which mediates ATP synthesis in the light, is inactive in darkened intact chloroplasts. Its light activation can be separated from the formation of the high energy condition, which results in ATP synthesis. After its activation, the enzyme catalyzes a reversible reaction.     

Studies on well-coupled Photosystem I-enriched subchloroplast vesicles — energy-dependent switching between two different active states of the proton-translocation adenosine triphosphatase

Single-turnover flash-induced ATP synthesis coupled to natural cyclic electron flow in Photosystem I-enriched subchloroplast vesicles (from spinach) was continuously followed by the luciferin-luciferase luminescence. The ATP yield per flash was maximal (1 ATP per s per 1000 Chl) around a flash frequency of 0.5–2 Hz. It decreased both at lower and higher flash frequencies. The decrease at high flash frequency was due to limitation by the electron-transfer rate, while the decrease at low flash frequency was directly due to intrinsic properties of the ATPase itself. Carbonylcyanide-p-trifluoromethoxyphenylhydrazone (FCCP) decreased the yield at low frequency more than at high frequency. The same behaviour was observed if electron transfer was artificially mediated by pyocyanin. If the ADP concentration was increased from 40 to at least 80 μM, or if the vesicles were preincubated with 5 mM dithiothreitol (DTT), the decrease of the yield at flash frequencies below 0.5 Hz was no longer observed. Incubation with DTT increased the rates of ATP hydrolysis and synthesis at any flash frequency. The decrease of the yield could be elicited again by addition of 50 nM FCCP. It is concluded that at low levels of the protonmotive force (Δ gm_H⁺), the ATPase is converted into an active ATP-hydrolyzing state in which ATP synthesis activity is decreased due to a decreased affinity towards ADP and/or to a decreased release of newly synthesized ATP, that can be cancelled by increasing the ADP concentration or by addition of DTT in the absence of uncoupler.     

31P NMR magnetization-transfer measurements of ATP turnover during steady-state isometric muscle contraction in the rat hind limb in vivo

31P NMR magnetization-transfer measurements have been used to measure the flux between ATP and inorganic phosphate during steady-state isometric muscle contraction in the rat hind limb in vivo. Steady-state contraction was obtained by supramaximal sciatic nerve stimulation. Increasing the stimulation pulse width from 10 to 90 ms, at a pulse frequency of 1 Hz, or increasing the frequency of a 10-ms pulse from 0.5 to 2 Hz resulted in an increase in the flux which was an approximately linear function of the increase in the tension-time integral. The flux showed an approximately linear dependence on the calculated free cytosolic ADP concentration up to an ADP concentration of about 90 microM. The data are consistent with control of mitochondrial ATP synthesis by the cytosolic ADP concentration and indicate that the apparent Km of the mitochondria for ADP is at least 30 microM.     

Increase in the translatable mRNA for acetylcholine receptor during embryonic development of Torpedo ocellata electric organ

Single-turnover flash-induced ATP synthesis in chloroplasts was measured in situ with the luciferin luminescence method. In dark-adapted chloroplasts the first flashes only induce ATP hydrolysis. Once the reversible ATPase is fully activated, ATP hydrolysis persists for extended periods of darkness and flash-induced ATP-synthesis is optimal even at flash frequencies lower than 0.1 Hz. About one molecule of ATP is formed per 1000 chlorophyll and flash. In a low frequency flashing regime under steady state conditions, the newly formed ATP is stable. There is no threshold light intensity for flash-induced ATP synthesis. The data are in agreement with models involving short-range interaction between electron transport and the coupling factor.     

Anthraniloyl ATP, a fluorescent analog of ATP, as a substrate for dynein ATPase and flagellar motility

We synthesized an anthraniloyl ATP (ant-ATP), which has a fluorescent anthraniloyl moiety at the OH group of ribose, to elucidate the mechanism of flagellar bend formation and its propagation in relation to the mechanochemical cycle of dynein ATPase. This fluorescent analog of ATP was efficiently hydrolyzed by 21 S dynein from sea urchin sperm flagella with Km = 7.6 microM, whereas the Km was 12 microM when ATP was used as the substrate. Similar Vmax values were obtained with both ATP and ant-ATP. Inhibition of the hydrolysis of ant-ATP by vanadate was a little smaller than that with ATP. Photosensitized cleavage of 21 S dynein heavy chains in the presence of ant-ATP and vanadate was also a little less efficient than that in the presence of ATP and vanadate. Ant-ATP also induced the disintegration of the trypsin-treated axoneme and the motility of demembranated sperm in a manner similar to ATP. When ATP was used as a substrate for the demembranated sperm, the apparent Michaelis constant for beat frequency (Km f) was 0.22 mM and the maximum frequency (fmax) was 36 Hz, whereas Km f) was 0.14 mM and fmax was 20 Hz for ant-ATP. Thus ant-ATP could be an efficient fluorescent analog of ATP for studying dynein ATPase and the mechanisms of flagellar motility.     

Functional recombination of dynein 1 with demembranated sea urchin sperm partially extracted with KC1.

Demembranated sea urchin sperm were extracted with 0.5 M KCl as described earlier and reactivated in a solution containing 1 mM ATP. Their flagellar beat frequency was approximately 13 Hz, while that of standard reactivated sperm which had not been extracted with KCl was approximately 31 Hz at 23°C. Addition of soluble dynein 1 caused a gradual increase in the flagellar beat frequency to approximately 25 Hz after 10 min at room temperature. This restoration of frequency occurred in the absence or presence of ATP. Examination by electron microscopy showed that, whereas KCl-extracted sperm were lacking the majority of the outer arms on the doublet tubules, they had regained most of their outer arms following incubation with soluble dynein 1.     

ATP synthesis by ATPase proteoliposomes from the thermophilic cyanobacterium Synechococcus 6716 by ionophore-induced electric potentials and proton gradients

ATP synthesis driven by low pre-established electric potentials and pH gradients is studied in large ATPase proteoliposomes, prepared from the ATPase complex and native lipids from the thermophilic cyanobacterium Synechococcus 6716. Electric potentials and pH gradients were achieved by valinomycin and nigericin, respectively, in the presence of a K⁺ gradient across the membrane. External base-pulses were also applied. In this system ATP synthesis driven by valinomycin-induced K⁺ influx, nigericin-induced internal acidification and by external base-pulses is demonstrated. Electric potentials and pH gradients of equivalent size lead to roughly similar ATP synthesis activities. ATP synthesis is optimal at 80–100 nM valinomycin and at 0.75−1 μM nigericin at the proper pre-set ion gradients. Uncoupler and DCCD inhibit ATP synthesis. Prior activation of the complex by thiol agents or trypsin was not required for synthesis activity. The ATP synthesis rate increases with the size of electric potential or pH gradient. The threshold value of the electrochemical gradient for significant ATP synthesis is about 30 mV. ATP production proceeds for more than 60 min. The generation of ionophore-induced electric potentials and pH gradients have been followed by oxonol VI and intraliposomal Neutral red, respectively. The extent of the absorbance changes of both probes is proportional to the size of electric potential or pH gradient. Ionophore-induced oxonol VI and Neutral red responses are stable for at least 30 min. The results are discussed in terms of membrane permeability and vesicle size.     

Electrochemotherapy of Mouse Sarcoma Tumors Using Electric Pulse Trains with Repetition Frequencies of 1 Hz and 5 kHz

Electrochemotherapy is an efficient local treatment of tumors that combines administration of a chemotherapeutic drug with the subsequent application of electric pulses to the tumor. Although no difference in clinical response of the treated tumors to the electrochemotherapy when using 1 Hz or 5 kHz repetition frequency was observed, it is mandatory to be aware of possible differences in the effectiveness of electrochemotherapy when using suboptimal doses of the drugs. Therefore, this study compares the antitumor effectiveness of electrochemotherapy using electric pulse trains with repetition frequencies of 1 Hz and 5 kHz at suboptimal drug doses of bleomycin or cisplatin. Electrochemotherapy of fibrosarcoma SA-1 subcutaneous tumors transplanted in A/J mice resulted in good antitumor effectiveness, but antitumor effectiveness was significantly better at 1 Hz repetition frequency than at 5 kHz. The platinum content was higher in tumors treated with a 1 Hz repetition frequency. The application of electric pulses to the tumors at a 5 kHz repetition frequency induced an immediate reduction in tumor perfusion, comparable to the reduction at 1 Hz but with faster reperfusion. The greater effectiveness of electrochemotherapy using electric pulse trains of 1 Hz compared to 5 kHz is due to the greater electroporative effect and longer time in which electroporated tumors are exposed to the two chemotherapeutic drugs. These differences are observed at suboptimal drug doses, whereas at optimal drug doses of bleomycin or cisplatin the antitumor effectiveness is the same, as demonstrated in clinical trials.     

Regulation of creatine kinase during steady-state isometric twitch contraction in rat skeletal muscle

In vivo 31P-NMR saturation transfer measurements of the creatine kinase exchange flux in the direction creatine phosphate----ATP were made in the gastrocnemius muscle of rats at rest and during steady-state isometric twitch contraction at frequencies from 0.25 to 2 Hz. There was no correlation between creatine kinase exchange flux and either free [ADP] or oxygen consumption, both of which increase with stimulation frequency. The flux was found to be nearly constant over all conditions at about 16 mM X s-1, 10-times greater than the highest estimated ATP turnover in this study. The kinetic properties of skeletal muscle creatine kinase in vivo are similar to, but not completely predictable from, the equilibrium exchange fluxes measured on the isolated enzyme. These results are not consistent with strong functional coupling between ATP synthesis and mitochondrial creatine kinase.     

Effects of Electromagnetic Fields on the Bioactivities of an Osteoblast-Like Cell Line (UMR-106)

In the present study, we first investigated the effects of various types of low-energy, low-frequency electromagnetic fields (EMFs) on DNA synthesis in UMR-106 osteoblast-like cells. The experimental groups were exposed to EMFs for 2 days (twice/day, 30 min/time), and DNA synthesis was measured. The results showed that the cells responded most sensitively to EMFs of some specific combinations of the parameters by an increase in DNA synthesis, implying that EMFs with a specific waveform rather than a complex one can be used in clinical electrotherapy. The parameters were as follows: pulsed electric field (PEF) with pulse width 0.2 ms, field strength 10 V/cm, frequency 125 Hz; sinusoidal electric field (SEF) with field strength 1 V/cm, frequency 10 Hz; and alternating magnetic field (AMF) with field density 0.5 mT, frequency 5 Hz. In addition to frequency, the field strength or field density within a suitable intensity scale played a dominant role in causing the DNA synthesis response. We then compared the effects of two kinds of fields, PEF and AMF, with the optimum parameters identified by the experiments, on alkaline phosphatase (ALP) activity, protein and collagen synthesis, and intracellular levels of cyclic adenosine monophosphate (cAMP). The results indicated that both fields could not only affect UMR-106 cells proliferation but could particularly affect a series of characteristic bioactivities of UMR-106 such as ALP activity and collagen synthesis. The intracellular cAMP levels were increased rapidly and greatly with exposure to both PEF and AMF, implying that the action of low-frequency EMFs proceeds via second messenger-dependent processes originating from signals at the cell membrane. The difference in action between PEF and AMF suggests that they may couple to the cell membrane in a partially different way.     

The Effect of the Stimulation Regime on Palaemon serratus Tail Muscle Energy Metabolism

The evolution of phosphometabolites was determined in the abdominal muscle of a crustacean Palaemon serratus during intermittent electrical stimulation at 1, 2 and 4 Hz and during natural escape behavior.The changes in AMP, IMP, phosphomonoesters, adenylate energy charge and ATP/ADP ratio were not affected by the frequency of electrical stimulation. On the contrary, changes in ATP, ADP and sum of adenylates depended on the stimulation protocol: degradation of ATP and accumulation of ADP were not significantly different after electrical stimulation at 2 and 4 Hz as compared to manual stimulation, but differed from the 1 Hz stimulation protocol values. The sum of adenylates decreased similarly after 2 and 4 Hz stimulation and manual protocols. The different exercise protocols did not produce any changes in AMP and IMP accumulation, ATP/ADP ratio and A.E.C. After manual stimulation, the phosphomonoester and phosphoarginine concentrations were similar to the variations observed in the all electrical stimulation protocols, while the Pi levels were similar to the variations observed in the 4 Hz stimulation protocol only. The NMR index decrease was significantly higher after the manual and 4 Hz stimulation protocols.     

The quasi-resonance dependence of the arrhythmogenic action of a low-frequency magnetic field on myocardial contractile activity

Non-monotonous quasi-resonance dependences of arising of arrhythmias on frequency and tension of magnetic field have been studied. Maximal effect was observed at 0.15 E and 40 Hz with 70% probability of the effect. The data obtained suggest that quasi-resonance effects of action of low-frequency magnetic fields are not limited to brain tissue and are mediated by the induced electric field.     

Electric field induced conformational changes of bacteriorhodopsin in purple membrane films

Electric field induced conformational changes of bacteriorhodopsin were studied in six types of dried film (randomly and electrically oriented membranes of purple as well as cation-depleted blue bacteriorhodopsin) by measuring the frequency dependence of the optical absorbance change and the dielectric dispersion and absorption. For the purple bacteriorhodopsin the optical absorbance change induced by alternating rectangular electric fields of ±300 kV/cm altered the sign twice in the frequency range from 0.001 Hz to 100 kHz (around 0.03 Hz and 100 kHz), indicating that the electric field induced conformational change in these samples consists of, at least, three steps. Similarly, it was found for the blue bacteriorhodopsin that at least two steps are involved. In accord with optical measurements, the dielectric behaviour due to alternating sinusoidal electric fields of±6kV/cm in the frequency range from 10 Hz to 10 MHz showed two broad dispersion/absorption regions, one below 1 kHz and the other around 10–100 kHz. This suggests that the conformational change of bacteriorhodopsin is also reflected by its dielectrical properties and that it is partially induced at 6 kV/cm. Including previous results obtained by analysis of the action of DC fields on purple membrane films, a model for a field-induced cyclic reaction for purple as well as blue bacteriorhodopsin is proposed. In addition it was found that there are electrical interactions among purple membrane fragments in dried films.     

Comparison of cardiac and 60 Hz magnetically induced electric fields measured in anesthetized rats

Extremely low frequency magnetic fields interact with an animal by inducing internal electric fields, which are in addition to the normal endogenous fields present in living animals. Male rats weighing about 560 g each were anesthetized with ketamine and xylazine. Small incisions were made in the ventral body wall at the chest and upper abdomen to position a miniature probe for measuring internal electric fields. The calibration constant for the probe size was 5.7 mm, with a flat response from at least 12 Hz to 20 kHz. A cardiac signal, similar to the normal electrocardiogram with a heart rate of about 250 bpm, was readily obtained at the chest. Upon analysis of its spectrum, the cardiac field detected by the probe had a broad maximum at 32–95 Hz. When the rats were exposed to a 1 mT, 60 Hz magnetic field, a spike appeared in the spectrum at 60 Hz. The peak-to-peak magnitudes of electric fields associated with normal heart function were comparable to fields induced by a 1 mT magnetic field at 60 Hz for those positions measured on the body surface (where induced fields were maximal). Within the body, or in different directions relative to the applied field, the induced fields were reduced (reaching zero at the center of the animal). The cardiac field increased near the heart, becoming much larger than the induced field. Thus, the cardiac electric field, together with the other endogenous fields, combine with induced electric fields and help to provide reference levels for the induced-field dosimetry of ELF magnetic field exposures of living animals. Bioelectromagnetics 18:317–323, 1997. © 1997 Wiley-Liss, Inc.     

Activation of Na+ and K+ pumping modes of (Na,K)-ATPase by an oscillating electric field

Serpersu and Tsong (Sepersu, E. H., and Tsong, T. Y. (1983) J. Membr. Biol. 74, 191-201; (1984) J. Biol. Chem. 259, 7155-7162) reported activation of a K+ pumping mode of (Na,K)-ATPase by an oscillating electric field (20 V/cm, 1.0 kHz). Their attempts to activate Na+ pumping at the same frequency were unsuccessful. We report here activation of a Na+ pumping mode with an oscillating electric field of the same strength as used previously (20 V/cm) but at a much higher frequency (1.0 MHz). At 3.5 degrees C and the optimal amplitude and frequency, the field-induced, ouabain-sensitive (0.2 mM ouabain incubated for 30 min) Rb+ influx ranged between 10 and 20 amol/red blood cell/h, and the corresponding Na+ efflux ranged between 15 and 30 amol/red blood cell/h, varying with the source of the erythrocytes. No Rb+ efflux nor Na+ influx was stimulated by the applied field in the frequency range 1 Hz to 10 MHz. These results indicate that only those transport modes that require ATP splitting under the physiological condition were affected by the applied electric fields, although the field-stimulated Rb+ influx and Na+ efflux did not depend on the cellular ATP concentration in the range 5 to 800 microM. Computer simulation of a four-state enzyme electroconformationally coupled to an alternating electric field (Tsong, T. Y., and Astumian, R. D. (1986) Bioelectrochem. Bioenerg. 15, 457-476; Tsong, T. Y. (1990) Annu. Rev. Biophys. Biophys. Chem. 19, 83-106) reproduced the main features of the above results.     

Role of purinergic cotransmission in the sympathetic control of arterial pressure variability in conscious rats

Previous studies have shown that the sympathetically mediated oscillations of arterial pressure (AP), the so-called Mayer waves, are shifted from 0.4 to 0.6 Hz after acute alpha-adrenoceptor blockade in conscious rats. This raises the possibility that, under physiological conditions, Mayer waves are mediated by the conjoint action of norepinephrine and other sympathetic cotransmitters. To evaluate the possible role of the cotransmitter ATP in determining the frequency of Mayer waves, AP and renal sympathetic nerve activity (RSNA) were simultaneously recorded in 10 conscious rats with cardiac autonomic blockade before and after acute blockade of P2 receptors with pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid. P2 receptor blockade did not alter the mean level and overall variability of AP and RSNA but shifted peak coherence between AP and RSNA from 0.43 +/- 0.02 to 0.22 +/- 0.01 Hz. A model of the sympathetic limb of the arterial baroreceptor reflex was designed to simulate Mayer waves at 0.2 and 0.6 Hz, with norepinephrine and ATP, respectively, acting as the sole sympathetic cotransmitter. When both cotransmitters acted in concert, a single oscillation was observed at 0.4 Hz when the gain ratio of the adrenergic to the purinergic components was set at 15. The model thus accounted for an important role for ATP in determining Mayer wave frequency, but not in sustaining the mean level of AP or controlling its overall variability.     

Reactivation of newt lung cilia: evidence for a possible temperature- and MgATP-induced activation mechanism.

Optimal conditions have been developed for the isolation and reactivation of highly coupled, demembranated ciliary axonemes from newt lungs [Hard, Cypher, and Schabtach, 1988, Cell Motil. Cytoskeleton 10:271-284]. In the present study, the motility of these cilia was further characterized by examining the effects of nucleotides, divalent cations, and temperature on beat frequency. When exposed to a reactivating solution containing Mg2+ and ATP, nearly 100% of the axonemes were motile and beat at frequencies of 0-50 Hz, depending on [MgATP] and temperature. Divalent cations were required for movement, with Mg2+ 2-3 times more effective than Ca2+. There was no absolute requirement for Ca2+ for motility. The beat frequencies obtained with fixed ATP and varying Mg2+ concentrations indicate that MgATP serves as the actual substrate. The effects of MgATP on beat frequency depended on the degree of mechanochemical coupling and temperature. When highly coupled preparations were reactivated at 21 degrees C, double reciprocal plots of beat frequency vs. [MgATP] were biphasic with extrapolated Fmax values of 22 and 44.8 Hz. However, when reactivated at 10 degrees C and 30 degrees C, linear plots were generated with Fmax values of 18.3 and 48.9 Hz, respectively. The beat frequencies of cultured cells and reactivated axonemes also varied biphasically with temperature. Our data suggest that newt lung respiratory cilia possess an intra-axonemal activation mechanism involving a temperature- and MgATP-induced transition between two distinct states whose maximum beat frequencies differ by 200-300%.     

Effects of viscosity and ATP concentration on the movement of reactivated sea-urchin sperm flagella.

Spermatozoa from the sea urchin, Lytechinus pictus, can be demembranated with solutions containing Triton X-100 and 5mM-CaCl2 and reactivated in ATP solutions containing low concentrations (10(-9)M) Of free Ca2+ ion to give symmetrical bending wave movements, even at very low ATP concentrations. At ATP concentrations of 0.01-0.02 mM the reactivated spermatozoa have beat frequencies near 1 Hz, nearly normal bend angles, and wave-lengths about 50% longer than normal. 2. The effects of increased viscosity, obtained by addition of methyl cellulose to the reactivation solutions, on bend angle and beat frequency decrease with decreasing ATP concentration, and become almost undetectable at 0.01 mM ATP. On the other hand, the effect of increased viscosity on wavelength shows relatively little change with ATP concentration, although it is noticeably reduced at 0.01 mM ATP. 3. These observations suggest that the beat frequency at low ATP concentrations is determined by an intrinsic rate-limiting process, in contrast to the viscocity-limited behaviour at high beat frequencies. Quantitative agreement with the experimental results is obtained with a model in which ATP concentration and viscosity each determine the rates of one step in a two-step reaction cycle which determines the beat frequency. 4. Two other models which can qualitatively explain the effects of ATP concentration and viscosity on flagellar beat frequency fail to show quantitative agreement with the experimental results. In one of these models, ATP concentration determines the maximum rate of shear between filaments. In the other, ATP concentration determines a time delay which is required to bring the active moment into phase with the elastic moments which would be expected to dominate the bending resistance at low beat frequencies.     

Effect of transcutaneous transcerebral electrostimulation as electroanesthesia on the beta-endorphin content of the cerebrospinal fluid and blood plasma

The beta-endorphin content was measured in the cerebrospinal fluid (CSF) and blood plasma of patients before and after 30 minutes of transcutaneous transcerebral electric stimulation in the electric anesthesia mode. The output current was biphasic and rectangular. It was composed of high-frequency pulse trains (peak-to-peak intensity 250-300 mA, frequency 167 kHz) modulated by low frequency (77 Hz). Electrical stimulation resulted in an appreciable increase in the beta-endorphin content in the CSF and blood plasma of patients. The data obtained attest to the intensification of the neuromodulator release to the CSF and blood plasma and to the involvement of the endorphinergic brain systems in the realization of the analgetic effect of transcutaneous transcerebral electric stimulation.