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PubMed1992

Effect of television advertising of alcohol on alcohol consumption and intentions to drive.

The alcohol consumption of 120 male and female college students was measured as they viewed a 90-min videotape of popular prime-time television programmes. Independent measures were the sex of the student, their drinker classification (light or moderate-heavy) and the number of alcohol advertisements (0, 6, 12) shown during the screening of the television programmes. Dependent measures were the number of drinks consumed, and the intentions of students to drive a motor vehicle after viewing the videotaped programmes. As predicted, males consumed more alcohol than females, and moderate-heavy drinkers consumed more than light drinkers. Male and female students who viewed six alcohol advertisements consumed more alcohol than students shown no alcohol advertisements or 12 alcohol advertisements. Analysis of intentions to drive after viewing the programmes revealed that the number of drinks consumed was not a significant covariate of driving intentions. Rather light drinkers of both sexes were less likely to intend to drive than moderate-heavy drinkers. Males exposed to alcohol advertisements were less likely to intend to drive than males who did not view alcohol advertisements. Different levels of exposure to alcohol advertisements did not influence the driving intentions of college females.

Journal Article↗
PubMed1996

Drivers' biased perceptions of the adverse consequences of drink-driving.

The decision to drink and drive may involve the subjective process of weighing the perceived risks of adverse consequences of the behaviour against perceived utility components. Deterrence theory proposes that an individual will refrain from drink-driving if the perceived chances of experiencing negative outcomes associated with the behaviour are high. Previous research has demonstrated that there may be a mechanism of judgmental bias which influences individuals' perceived probabilities of rarely occurring events. In general driver age and gender have been shown independently to be both indicative and non-indicative for the operation of the bias in terms of subjective perceptions of driver skill, safety and accident involvement. Little evidence has been presented to describe the nature of the bias in the specific domain of drink-driving. Responses from more than 1000 UK drivers were examined to establish whether a system of bias operated for judgments of the likelihood of experiencing several possible adverse consequences of drink-driving across males/females, age groups and offenders/non-offenders. In general drivers were found to perceive themselves as less likely than the average driver to be accident involved while impaired and non-impaired by alcohol. Drivers reporting previous drink-driving behaviour indicated the greatest bias. The age and gender of the driver, independently and in interaction, were not shown to be important in the operation of these perceptual inconsistencies. Findings are discussed for implications of deterrence based drink-driving counter-measures.

Journal Article↗
PubMed1994

Image reconstruction using non-adjacent drive configurations.

The standard 'back projection' image reconstruction algorithm developed at Sheffield uses data obtained by passing current between adjacent pairs of electrodes and measuring voltage differences between the remaining pairs. Previously it has been argued that this configuration gives the best resolution compared to all other bipolar drive configurations. However, it also gives the worst signal to noise ratio data and it is possible that under conditions of poor signal to noise ratio it may be advantageous to use an alternative drive configuration, even at the expense of resolution. A general image reconstruction algorithm for any bipolar drive configuration has been produced. Reconstruction algorithms for the adjacent, cross (drive electrodes 90 degrees apart) and polar drive (drive electrodes 180 degrees apart) have been examined and compared in terms of their resolution and noise performance.

Algorithms↗
PubMed2006

Pseudo-polar drive patterns for brain electrical impedance tomography.

Brain electrical impedance tomography (EIT) is a difficult task as brain tissues are enclosed by the skull of high resistance and cerebrospinal fluid (CSF) of low resistance, which makes internal resistivity information more difficult to extract. In order to seek a single source drive pattern that is more suitable for brain EIT, we built a more realistic experimental setting that simulates a head with the resistivity of the scalp, skull, CSF and brain, and compared the performance of adjacent, cross, polar and pseudo-polar drive patterns in terms of the boundary voltage dynamic range, independent measurement number, total boundary voltage changes and anti-noise performance based on it. The results demonstrate that the pseudo-polar drive pattern is optimal in all the aspects except for the dynamic range. The polar and cross drive patterns come next, and the adjacent drive pattern is the worst. Therefore, the pseudo-polar drive pattern should be chosen for brain EIT.

Brain↗
PubMed2002

Sperm competition and the dynamics of X chromosome drive: stability and extinction.

Several empirical studies of sperm competition in populations polymorphic for a driving X chromosome have revealed that Sex-ratio males (those carrying a driving X) are at a disadvantage relative to Standard males. Because the frequency of the driving X chromosome determines the population-level sex ratio and thus alters male and female mating rates, the evolutionary consequences of sperm competition for sex chromosome meiotic drive are subtle. As the SR allele increases in frequency, the ratio of females to males also increases, causing an increase in the male mating rate and a decrease in the female mating rate. While the former change may exacerbate the disadvantage of Sex-ratio males during sperm competition, the latter change decreases the incidence of sperm competition within the population. We analyze a model of the effects of sperm competition on a driving X chromosome and show that these opposing trends in male and female mating rates can result in two coexisting locally stable equilibria, one corresponding to a balanced polymorphism of the SR and ST alleles and the second to fixation of the ST allele. Stochastic fluctuations of either the population sex ratio or the SR frequency can then drive the population away from the balanced polymorphism and into the basin of attraction for the second equilibrium, resulting in fixation of the SR allele and extinction of the population.

Animals↗
PubMed1997

Dementia and driving: an attempt at consensus.

The number of older drivers in Sweden will be rapidly increasing during the next decades. A possible relationship exists between the increased relative crash risk of older drivers and the prevalence of age-related diseases such as dementia. However, a clear-cut policy for evaluating driving competence in demented persons is still lacking. In recognition of this fact, the Swedish National Road Administration invited a group of researchers to formulate a consensus on the issue of driving and dementia. This consensus document is aimed at providing primary care physicians with practical advice concerning the assessment of cognitive status in relation to driving. Suggestions are based on a review of existing research and discuss the use of general and driving-specific sources of information available to the physician. Consensus was reached on the statement that a diagnosis of moderate to severe dementia precludes driving and that certain individuals with mild dementia should be considered for a specialized assessment of their driving competence.

Aged↗
PubMedDate not supplied

A safe automatic driving method for a continuous flow ventricular assist device based on motor current pulsatility: in vitro evaluation.

We previously reported that detection of two specific points (the t-point and the s-point) in the relationship between pump speed and Motor Current Amplitude index (ICA) indicates the safe driving range for a continuous-flow ventricular assist device (CFVAD). During the first stage of the present experiment, the characteristic curves relating pump speed and ICA were determined by varying preload (left atrial pressure: -6 to 30 mm Hg), afterload (total circuit resistance: 890 to 3,180 dyne x sec x cm(-5)), and contractility of the left ventricle (total circuit flow: 0.5 to 2.1 L/min). These data showed that an ICA value of 0.18 was always located between the t- and s-points. During the second stage of the experiment, we developed an automatic driving program to control pump speed by maintaining ICA at 0.18. This program was able to drive the CFVAD, without exhibiting regurgitant flow or sucking, under various driving conditions in the mock circulation. Pump speed stabilized within 1 minute after varying the drive conditions. This sensorless method of driving the CFVAD by using a target ICA proved feasible and effective for safe automatic control, within our mock circulation.

Algorithms↗
PubMed1993

Ventilatory drive and carbon dioxide response in ventilatory failure due to myasthenia gravis and Guillain-Barré syndrome.

OBJECTIVE: To test the hypothesis that either decreased ventilatory drive or decreased CO2 responsiveness accounts for the hypoventilation observed in patients during acute ventilatory failure from myasthenia gravis or Guillain-Barré syndrome. DESIGN: Prospective, consecutive case series evaluating trials of ventilatory muscle performance, ventilatory drive, and CO2 response in patients during recovery from ventilatory failure until they were weaned from mechanical ventilation. SETTING: Neurosciences critical care unit in a university hospital. PATIENTS: Seven intubated, mechanically ventilated patients with myasthenia gravis or Guillain-Barré syndrome. INTERVENTIONS: Patients repeatedly performed mechanically unsupported, spontaneous breathing trials to the limits of endurance. After spontaneous breathing trials, patients underwent CO2 rebreathing studies. MEASUREMENTS AND MAIN RESULTS: Seventy-three breathing trials were performed in three patients with Guillain-Barré syndrome and four patients with myasthenia gravis. Patients were unable to sustain spontaneous ventilation in 55 trials averaging 27 +/- 5 mins. In these trials, significant increases occurred in mean end-tidal CO2 (41 +/- 1 to 44 +/- 1 torr [5.6 +/- 0.1 to 6.0 +/- 0.1 kPa]) and respiratory rate (31 +/- 1 to 35 +/- 1 breaths/min, p < .01). Ventilatory drive (as measured by airway occlusion pressure for 100 msecs) increased significantly p < .01 from 3.7 +/- 0.3 to 4.9 +/- 0.3 cm H2O. The response of airway occlusion pressure to CO2 rebreathing after these trials was 0.33 +/- 0.07 cm H2O/sec/mm Hg, while the minute ventilation response to CO2 rebreathing was only 0.30 +/- 0.06 L/min/mm Hg. CONCLUSIONS: These results suggest that ventilatory drive increases during acute hypoventilation, and the ventilatory drive response to CO2 remains intact, even when the minute ventilation response to CO2 is poor. Therefore, a decrease in ventilatory drive or CO2 response is unlikely to account for hypoventilation during ventilatory failure in patients with myasthenia gravis or Guillain-Barré syndrome.

Acute Disease↗
PubMed1999

An assessment of the clinical relevance of serum testosterone level determination in the evaluation of men with low sexual drive.

PURPOSE: We evaluated the relationship between sexual drive and serum testosterone level among men with erectile dysfunction. MATERIALS AND METHODS: A retrospective medical record review of 180 men who attended a hospital based erectile dysfunction clinic between April 1997 and January 1998 was performed. Sexual drive was assessed using the Brief Sexual Function Inventory questionnaire, and serum total and free testosterone levels were measured. RESULTS: A total of 108 complete records were included in this report. Mean patient age plus or minus standard deviation was 59.5+/-10.2 years (range 33 to 79). Of the men 55 (50.9%) had low, 38 (35.2%) moderate and 15 (13.9%) high sexual drive. Mean sexual drive, bothersomeness and total sexual function scores among the groups were significantly different (p<0.001). Mean serum total testosterone levels among men with low, moderate and high sexual drive were 2.8, 3.2 and 3.4 mg./ml. (normal 2.8 to 8.8), respectively, and mean free testosterone levels were 9.1, 9.5 and 11.4 pg./ml. (normal 8.7 to 54.7), respectively. Differences among means were not statistically significant. As a screening test for low sexual drive, low total testosterone had a positive predictive value, negative predictive value and yield of 59.2, 55.9 and 26.9%, respectively.

Adult↗
PubMed2006

Modeling of muscle motor unit innervation process correlation and common drive.

Concurrently active motor units (MUs) of a given muscle can exhibit a certain degree of synchronous firings, and a certain degree of common variation in their firing rates. The former property is referred to as motor unit synchrony in the literature, which is termed motor unit innervation process (MUIP) correlation in this study. The latter is referred to as motor unit common drive and can be quantified by the common drive coefficient, which is the correlation coefficient between the smoothed firing rates of the two MUs. Both properties have important roles and implications in the generation and resulting characteristics of the myoelectric signal and for the development of signal processing algorithms in myoelectric signal (MES) applications. In order to study these implications and characteristics, in this paper estimation procedures are developed to quantify the degree of MUIP correlation and common drive as functions of physiological parameters. Also, the interaction between MUIP correlation and motor unit common drive is studied in a physiologically realistic simulation model. Neurons modeled by Hodgkin-Huxley systems form the framework of the simulation model in which excitation and synaptic characteristics can be modified. MUIP correlation and common drive degree and interaction are studied through a number of simulations. To support the simulation results, experimental in vivo motor unit trains were collected at low levels of contraction from 11 subjects, and decomposed into the constituent unit trains giving 50 concurrently active motor unit pairs. The simulation demonstrated that the innervation process correlation coefficient is controlled primarily by the postsynaptic conductance, gsyn, and was less than 0.05 mS/cm2 for realistic values of gsyn. The common drive was found to be controlled by the exciting neuron input with no statistically significant interaction between it and the MUIP correlation. The experimental data gave results in close agreement with those of the simulation.

Action Potentials↗
PubMedDate not supplied

The effect of monovision contact lens wear on driving performance.

BACKGROUND: A number of studies have highlighted the problems with driving reported by wearers of monovision contact lens corrections. In this study, we wished to investigate this further, by determining whether driving performance as measured on the open road under daytime conditions is worse when drivers wear their monovision contact lenses compared to their habitual correction. METHODS: Thirteen subjects with healthy eyes and corrected visual acuity of 6/6 were selected. Each had worn monovision contact lenses for at least three months. All subjects had their driving performance assessed while driving their own vehicles on an open road course, with both monovision contact lenses and their other habitual correction (spectacles or unaided). RESULTS: No statistically significant differences were found in driving performance when subjects wore their monovision contact lenses compared to when they wore their habitual distance correction. CONCLUSIONS: The results indicate that monovision does not adversely affect driving performance in daylight hours for adapted wearers. However, limitations in the study design are acknowledged, including the relatively small sample size, lack of standardisation of the habitual correction and the use of adapted wearers. Future studies are recommended to investigate these issues further.

Journal Article↗
PubMed2000

Endogenous excitatory drive to the respiratory system in rapid eye movement sleep in cats.

A putative endogenous excitatory drive to the respiratory system in rapid eye movement (REM) sleep may explain many characteristics of breathing in that state, e.g. its irregularity and variable ventilatory responses to chemical stimuli. This drive is hypothetical, and determinations of its existence and character are complicated by control of the respiratory system by the oscillator and its feedback mechanisms. In the present study, endogenous drive was studied during apnoea caused by mechanical hyperventilation. We reasoned that if there was a REM-dependent drive to the respiratory system, then respiratory activity should emerge out of the background apnoea as a manifestation of the drive. Diaphragmatic muscle or medullary respiratory neuronal activity was studied in five intact, unanaesthetized adult cats who were either mechanically hyperventilated or breathed spontaneously in more than 100 REM sleep periods. Diaphragmatic activity emerged out of a background apnoea caused by mechanical hyperventilation an average of 34 s after the onset of REM sleep. Emergent activity occurred in 60 % of 10 s epochs in REM sleep and the amount of activity per unit time averaged approximately 40 % of eupnoeic activity. The activity occurred in episodes and was poorly related to pontogeniculo-occipital waves. At low CO2 levels, this activity was non-rhythmic. At higher CO2 levels (less than 0.5 % below eupnoeic end-tidal percentage CO2 levels in non-REM (NREM) sleep), activity became rhythmic. Medullary respiratory neurons were recorded in one of the five animals. Nineteen of twenty-seven medullary respiratory neurons were excited in REM sleep during apnoea. Excited neurons included inspiratory, expiratory and phase-spanning neurons. Excitation began about 43 s after the onset of REM sleep. Activity increased from an average of 6 impulses s-1 in NREM sleep to 15.5 impulses s-1 in REM sleep. Neuronal activity was non-rhythmic at low CO2 levels and became rhythmic when levels were less than 0.5 % below eupnoeic end-tidal levels in NREM sleep. The level of CO2 at which rhythmic neuronal activity developed corresponded to eupnoeic end-tidal CO2 levels in REM sleep. These results demonstrate an endogenous excitatory drive to the respiratory system in REM sleep and account for rapid and irregular breathing and the lower set-point to CO2 in that state.

Animals↗
PubMed1994

The effect of valve type and drive line dP/dt on hemolysis in the pneumatic ventricular assist device.

The objective of this experiment was to investigate the relationship between blood damage and drive line dP/dt and valve type in the pneumatic ventricular assist device. Two mock circulatory loops were assembled using 70-ml Penn State pneumatic ventricular assist devices, one fitted with convexo-concave (CC) valves and one fitted with monostrut (MS) valves. Use of a compliance chamber established three ranges of drive line dP/dt values. Using bovine blood and the methods of generalized estimating equations, it was found that drive line dP/dt was significantly associated with the index of hemolysis (p = 0.00): the lower drive line dP/dt values yielded lower indices of hemolysis. In addition, this association differed between MS and CC valves (p = 0.01); the MS valves consistently yielded a higher index of hemolysis than the CC valves across all drive line dP/dt ranges. However, the relative hemolytic potential of each valve type became much closer at low drive line dP/dt values (2,000-3,000 mm Hg).

Animals↗
PubMed2006

Influence of drive cycle length on initiation of ventricular fibrillation during implantable cardioverter defibrillator threshold testing.

BACKGROUND: Programmed electrical stimulation of the heart as a method to induce tachyarrhythmias has been described since the 1960s. To date, no study has examined optimal drive cycle length in the induction of ventricular fibrillation (VF) during defibrillation threshold testing after implantable cardioverter-defibrillator placement. We hypothesized that longer drive cycle length, by means of the longer action potential duration, would promote intramyocardial phase 2 reentry and facilitate induction of VF. METHODS: Fifty consecutive implants were randomized in a prospective crossover format for this study. The group consisted of 40 men and 10 women, with each patient receiving either a 400 or 600 ms initial drive train prior to 1.2 J internal shock on the T wave with a goal to induce ventricular fibrillation. The timing of the T wave shock was determined by measuring the interval from the beginning of the QRS to the apex of the T wave in lead II. Successful inductions were defibrillated via the cardioverter defibrillator. Patients were then crossed over and the protocol repeated. RESULTS: Twenty of 23 (87%) patients were successfully induced into VF in the initial 400 ms drive train arm whereas 22 of 27 (81%) were successfully induced in the 600 ms arm. Thus, a total of 44 (88%) patients were successfully induced at 400 ms, 41 (82%) patients were successfully induced at 600 ms, and 2 (4%) patients were not inducible at either cycle length, but were inducible with 50 Hz ventricular stimulation. However, no significant difference was noted between the two groups. CONCLUSION: No investigation to date has questioned whether a relationship exists between drive cycle length and initiation of ventricular fibrillation. Our study addresses this question, though negative for difference between 400 and 600 ms drive trains. Further research into optimal strategies for inducing ventricular fibrillation will minimize patient sedation time and discomfort while undergoing defibrillator threshold testing.

Aged↗
PubMed1991

Respiratory-associated rhythmic firing of midbrain neurones in cats: relation to level of respiratory drive.

1. We recorded phrenic nerve activities and single unit firing of mesencephalic neurones in unanaesthetized supracollicularly decerebrated, paralysed and ventilated cats, in which vagi and carotid sinus nerves had been ablated. We made these measurements first at low levels of respiratory drive associated with normal PCO2 levels, then with increased respiratory drive and levels of phrenic activity produced by hypercapnia or by carotid sinus nerve stimulation. 2. We found that at least a quarter of the neurones in the central tegmental field of the mesencephalon, which were irregularly tonic or silent at low respiratory drives, developed a rhythmic increase of firing associated with each respiration. There appeared to be a threshold at about 50% of maximum respiratory activity, below which the respiratory-associated rhythm did not occur. Above this level, neuronal firing increased in graded fashion with increasing magnitude of respiratory activity. The latency from onset of phrenic activity to onset of increased neuronal firing was quite long (1.0 s) at drives just above the threshold but shortened to as little as 0.3 s as drive increased towards its maximum. 3. Cutting the spinal cord at C1-C2 had no effect on the ability of increased respiratory activity to generate a respiratory-associated rhythm in mesencephalic neurones. 4. Short-lasting anaesthesia with the agent Saffan caused mesencephalic neurones to lose the respiratory-associated rhythm with little change in phrenic activity and no change in respiratory cycle timing. 5. We also found a mesencephalic response to ventilator-induced chest expansion. The latency of the response from onset of expansion, indexed by fall of airway PCO2, to onset of neurone firing was shorter (0.2 s) than that found with the respiratory-associated rhythm. In seventeen neurones we found both the respiratory-associated rhythm and the independent ventilator-associated rhythm. 6. We interpret our findings to show that the respiratory-associated rhythmic firing of midbrain neurones is not primarily involved in generation or modulation of the motor function of the respiratory oscillator. We believe, instead, that these neurones are part of a sensory pathway conveying information about the magnitude of central neural respiratory drive, as well as spinally transmitted information from receptors in the chest wall, to thalamus and cortex. We suggest that the sensation ultimately generated may be that of 'air hunger' or dyspnoea.

Action Potentials↗
PubMed1992

Coherence between the sympathetic drives to relaxed and contracting muscles of different limbs of human subjects.

1. This study was undertaken to quantify the simultaneous sympathetic drives to muscles in the two legs of human subjects, and to elucidate the extent to which a common drive determines sympathetic outflow to different limbs at rest, during apnoea and during voluntary contractions. 2. Sympathetic efferent activity was recorded simultaneously from fascicles of both peroneal nerves, innervating the pretibial flexor muscles. At rest the similarity was quantified for a sample of records by manual measurement of equivalent bursts in the two recordings, and for all records by cross-correlation and power spectral analysis of the two recordings. During contractions, only the latter method was used. 3. At rest the correlation coefficient for the relationship between the burst amplitudes for the two recordings was 0.72 (S.D. 0.1). For the same sequences, the computed coherence between the two recordings was 85.6% (S.D. 6.7%) at the cardiac period. There was a statistically significant linear relationship between these two measures of similarity, and this was stronger when data from sequences recorded during apnoea were included in the analysis. At rest the mean difference in coherence between consecutive sequences with no intervening manoeuvre (apnoea, contraction, change in recording site) was 4.2% (S.D. 4.3%). In only two of forty-nine such instances was the difference in coherence > 10%. 4. Apnoea at end-expiration increased the amplitude and frequency of sympathetic bursts and increased the similarity between the two recordings. The correlation coefficients increased from a mean of 0.72 at rest to 0.89 during apnoea. Coherence increased from a mean of 82.1% at rest to 91.9% during apnoea. 5. On the right side, graded voluntary contractions were performed at 5, 10, 20 or 30% maximal force using the muscle innervated by the fascicle from which the recording was made. The coherence between the recordings made from the right and left legs decreased by > 10% at each contraction level. Pooling the data for all contractions, there was a significant decrease in power at the cardiac frequency in the sympathetic recording from the contracting leg. Contraction of a synergist or antagonist at 10% maximum produced negligible changes in coherence. 6. It is concluded that, at rest, homologous muscles of the lower limbs are subject to a common drive and that, during apnoea, this common drive can dominate the sympathetic outflow to the virtual exclusion of regional drives. During voluntary activity, the importance of this common drive is lessened, presumably because of regionally specific changes involving the contracting muscle.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed2006

Cell domain-dependent changes in the glutamatergic and GABAergic drives during epileptogenesis in the rat CA1 region.

An increased ratio of the glutamatergic drive to the overall glutamatergic/GABAergic drive characterizes the chronic stage of temporal lobe epilepsy (TLE), but it is unclear whether this modification is present during the latent period that often precedes the epileptic stage. Using the pilocarpine model of TLE in rats, we report that this ratio is decreased in hippocampal CA1 pyramidal cells during the early phase of the latent period (3-5 days post pilocarpine). It is, however, increased during the late phase of the latent period (7-10 days post pilocarpine), via cell domain-dependent alterations in synaptic current properties, concomitant with the occurrence of interictal-like activity in vivo. During the late latent period, the glutamatergic drive was increased in somata via an enhancement in EPSC decay time constant and in dendrites via an increase in EPSC frequency and amplitude. The GABAergic drive remained unchanged in the soma but was decreased in dendrites, since the drop off in IPSC frequency was more marked than the increase in IPSC kinetics. Theoretical considerations suggest that these modifications are sufficient to produce interictal-like activity. In epileptic animals, the ratio of the glutamatergic drive to the overall synaptic drive was not further modified, despite additional changes in synaptic current frequency and kinetics. These results show that the global changes to more glutamatergic and less GABAergic activities in the CA1 region precede the chronic stage of epilepsy, possibly facilitating the occurrence and/or the propagation of interictal activity.

Algorithms↗
PubMed2006

Oppositely directed H+ gradient functions as a driving force of rat H+/organic cation antiporter MATE1.

Recently, we have isolated the rat (r) H(+)/organic cation antiporter multidrug and toxin extrusion 1 (MATE1) and reported its tissue distribution and transport characteristics. Functional characterization suggested that an oppositely directed H(+) gradient serves as a driving force for the transport of a prototypical organic cation, tetraethylammonium, by MATE1, but there is no direct evidence to prove this. In the present study, therefore, we elucidated the driving force of tetraethylammonium transport via rMATE1 using plasma membrane vesicles isolated from HEK293 cells stably expressing rMATE1 (HEK-rMATE1 cells). A 70-kDa rMATE1 protein was confirmed to exist in HEK-rMATE1 cells, and the transport of various organic cations including [(14)C]tetraethylammonium was stimulated in intracellular acidified HEK-rMATE1 cells but not mock cells. The transport of [(14)C]tetraethylammonium in membrane vesicles from HEK-rMATE1 cells exhibited the overshoot phenomenon only when there was an outwardly directed H(+) gradient, as observed in rat renal brush-border membrane vesicles. The overshoot phenomenon was not observed in the vesicles from mock cells. The stimulated [(14)C]tetraethylammonium uptake by an H(+) gradient [intravesicular H(+) concentration ([H(+)](in)) > extravesicular H(+) concentration ([H(+)](out))] was significantly reduced in the presence of a protonophore, carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP). [(14)C]tetraethylammonium uptake was not changed in the presence of valinomycin-induced membrane potential. These findings definitively indicate that an oppositely directed H(+) gradient serves as a driving force of tetraethylammonium transport via rMATE1, and this is the first demonstration to identify the driving force of the MATE family. The present experimental strategy is very useful in identifying the driving force of cloned transporters whose driving force has not been evaluated.

Animals↗