Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “R:FR”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 253 records · Page 14Linked to original sources
PubMed2001

Effect of ischemic preconditioning on myocardial protection in coronary artery bypass graft patients : can the free radicals act as a trigger for ischemic preconditioning?

OBJECTIVE: To investigate the interrelationship of free radicals (FRs), ischemic preconditioning (IP), and hemodynamic function in coronary artery bypass graft (CABG) patients. DESIGN: Prospective, randomized, and controlled clinical study. PATIENTS: Forty CABG patients were randomized into an IP group (n = 20) and a control group (n = 20). INTERVENTION: The IP group was preconditioned with two cycles of two-min ischemia followed by 3-min reperfusion before cross-clamping. MEASUREMENT AND RESULTS: FR content in coronary sinus blood was measured directly using alpha-phenyl-N-tert-butylnitrone-electron spin-trapped spectroscopy. A small amount of FRs was generated after the IP protocol (5.6% above the baseline) but not in control subjects. A larger amount was generated 10 min after declamping in both groups (8.4% in IP protocol and 7.7% in control subjects). Hemodynamic function recovered better in the IP group at 1 h and 6 h after declamping. There was a significant negative correlation between FR generation after declamping and left ventricular stroke work index (LVSWI) at 1 h and 6 h after declamping (r = -0.71 and - 0.59, respectively) in the control subjects but not in the IP group. There was a significant positive correlation between FR generation after the IP protocol and cardiac index at 1 h and 6 h (r = 0.50 and 0.61, respectively) and LVSWI at 1 h and 6 h (r = 0.56 and 0.54, respectively) after declamping in the IP group but not in the control subjects. CONCLUSION: FR generation after the operation correlates with ventricular functional depression in CABG patients. IP protects the stunning heart but does not alter FR generation. The association of better hemodynamic recovery after CABG with FR generation during the IP period suggests that FRs might act as one of the triggers for IP.

Aged↗
PubMed1968

Differences in Photoresponse and Phytochrome Spectrophotometry Between Etiolated and De-etiolated Pea Stem Tissue.

Morphologically similar pea plants having a 4-fold difference in spectrophoto-metrically detectable phytochrome can be produced by pretreatment of etiolated plants with red light (R) or with red and far-red light combined (RF). A search for response differences which could be ascribed to differences in phytochrome content has resulted only in the establishment of differences due to de-etiolation. Segments of etiolated plants differ from those of plants de-etiolated by R and RF pretreatments in 2 ways. Segments from etiolated plants appear to respond rapidly to the far-red absorbing form of phytochrome (P(FR)), while segments from de-etiolated plants do not respond rapidly to P(FR). This statement is based upon 2 observations: (i) the red light induced growth inhibition in segments from etiolated plants rapidly escapes reversibility by far-red light, while with segments from R or RF pretreated plants, the red light effect is fully reversed by subsequent far-red light for up to 2 hr; and (ii) segments from etiolated plants were inhibited to a greater degree than were segments from RF pretreated plants when various photostationary state levels of P(FR) were maintained for 30 or 90 min and then removed by photoconversion to P(R). The in vivo nonphotochemical transformation curves of the phytochrome of etiolated and RF pretreated plants appear to differ in 2 related respects: (i) the amount of phytochrome destroyed in de-etiolated tissue is greater than that in etiolated tissue, perhaps as a result of the fact that (ii) the rate and extent of apparent reversion of P(FR) to P(R) in etiolated tissue is about twice that in de-etiolated tissue.

Journal Article↗
PubMed1988

Interaction of temperature with other environmental factors in controlling the development of plants.

Development is the ordered sequence of changes in plant form and phenology that occurs through time. As such it is distinguished from that of growth and includes the succession of ontogenetic stages as well as the initiation of leaves, shoots and roots. It is more useful to look at rates of development as functions of environmental influences rather than, for example, total number of days to a given stage. It is often found that linear, or close to linear, relationships are found between rates and temperature, photoperiod and the duration of cold temperatures. These ideas are treated theoretically and illustrated with data from an experiment where wheat was grown at ten sites in Britain. We conclude that temperature is the most important factor governing differences in developmental rates between sites and sowing dates, especially for later stages of development. Variation in the timing of earlier stages depends on either exposure to photoperiods of different lengths or on the degree of vernalization of the plants. Calculation is made of the maximum effectiveness of these environmental factors in shortening the vegetative phases in a range of wheat cultivars and the basis of their interaction is also explored. For wheat it seems that they act multiplicatively in their effect on developmental rate. The rate at which plants produce their leaves is important in canopy development. The sensitivity of the rate of leaf emergence, measured in thermal time, has been linked to the rate at which daylength changes (d phi/dt). A possible mechanism may involve plants responding to the ratio of light in the red (R, ca 660 nm) and far-red (FR, ca 730 nm) wavebands (R/FR). This ratio decreases when d phi/dt is becoming more negative and vice versa. Linkage can be found between the change in R/FR at twilight and commensurate changes in calculated phytochrome photoequilibria. Thus, the possibility exists that phytochrome may be involved in modulating the leaf production rate in response to different sowing dates. Alternatively, variation in rate of leaf production may be through changes in the base temperature, in response to the 'spectrum' of temperatures the plants experience during development. Thus, any involvement of photoperiod in this response may be spurious. Controlled environment studies of leaf emergence tend to support this latter interpretation as does analysis of experiments from three European sites.

Edible Grain↗
PubMed2002

Precise real-time correction of anger camera deadtime losses.

An earlier paper dealt with modeling of the camera in terms of the resolving times, tau0 and T, of the paralyzable detector and nonparalyzable computer system, respectively, for the case of a full energy window. A second paper presented a decaying source method for the accurate real-time measurement of these resolving times. The present paper first shows that the detector system can be treated as a single device with a resolving time tau0 dependent on source distribution. It then discusses camera operation with an energy window, window fraction being fw = Rp/Rd < or = 1, where Rd and Rp are the detector and pulse-height-analyzer (PHA) outputs, respectively. The detector resolving time is shown to vary with window fraction according to tau0p = tau0p/f(w), while T is unaffected, so that operation may be paralyzable or nonparalyzable depending on window setting and the ratio kT = T/tau0. Regions of interest are described in terms of the ROI fraction, fr =Rr IR < or = 1, and resolving time, tau0r = tau0p/fr, where R and Rr are the recorded count rates for the field-of-view and the region-of-interest, respectively. As tau0p and tau0r are expected to vary with input rate, it is shown that these can be measured in real-time using the decaying source method. It is then shown that camera operation both with fw < or = 1 and fr < or = 1 can be described by the simple paralyzable equation r = ne(-n), where n=Nwtau0p=Nrtau0r and r=Rptau0p=Rrtau0r, Nw, and Nr being the input rates within the energy window and the region of interest, respectively. An analytical solution to the paralyzable equation is then presented, which enables the input rates Nw = n/tau0p and Nr = n/tau0r to be obtained correct to better than 0.52% all the way up to the peak response point of the camera.

Equipment Design↗
PubMed2006

Does tibial rotation correlate with femoral anteversion? Implications for hip arthroplasty.

The aim of the study was to assess the magnitude and variability of rotation of ipsilateral femur and tibia and to identify the existence of rotational correlations. Femoral rotation (FR) and tibial rotation (TR) were measured with computed tomography in 151 consecutive patients when total hip arthroplasty was planned. Median FR was 14 degrees (range, -23 degrees to 91 degrees ) and median TR was 38 degrees (range, 15 degrees -76 degrees ). Femoral rotation was significantly higher in females, in left femora, in the presence of secondary osteoarthritis, and in hip dysplasia. Tibial rotation was significantly higher in females. Femoral rotation and TR positively correlated (r = 0.2963, P = .0001). The magnitude of TR and FR was found to be dependent on each other. Disregarding the variability and magnitude of TR may result in asymmetrical foot positioning after correction of FR during total hip arthroplasty.

Adult↗
PubMed2003

International Conference on Harmonisation: guidance on Q1D bracketing and matrixing designs for stability testing of new drug substances and products; availability. Notice.

The Food and Drug Administration (FDA) is announcing the availability of a guidance entitled "Q1D Bracketing and Matrixing Designs for Stability Testing of New Drug Substances and Products." The guidance was prepared under the auspices of the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH). This guidance is an annex to an ICH guidance entitled "Q1A(R) Stability Testing of New Drug Substances and Products" (66 FR 56332, November 7, 2001). It is intended to provide guidance on the application of reduced designs (i.e., bracketing and matrixing) for stability studies conducted in accordance with the principles outlined in ICH Q1A(R).

Chemistry, Pharmaceutical↗
PubMed2001

Scaling relations for granular flow in quasi-two-dimensional rotating cylinders.

An experimental study of the flow of different materials (steel balls, glass beads, and sand) in quasi-two-dimensional rotating cylinders is carried out using flow visualization. The flow in the rotating cylinder comprises of a thin-flowing surface layer with the remaining particles rotating as a fixed bed. Experimental results indicate that the scaled layer thickness increases with increasing Froude number (Fr=omega(2)R/g, where omega is the angular speed, R is the cylinder radius, and g the acceleration due to gravity) and with increase in size ratio (s=d/R, where d is the particle diameter). The free surface profile, is nearly flat at low Fr and becomes increasingly S shaped with increasing Fr. The layer thickness profiles, which are symmetric at low Fr become skewed at high values of Fr and small s. The dynamic angles of repose for all the materials studied show a near-linear increase with rotational speed (omega). Scaling analysis of the experimental data shows that the shape of the scaled surface profiles and the scaled layer thickness profiles are nearly identical when Froude number and size ratio are held constant, for each material. The surface profiles and layer thickness profiles are also found to be nearly independent of the material used. The dynamic angle of repose (beta), however, does not scale with Fr and s and depends on the particle properties. The experimental results are compared to continuum models for flow in the layer. The models of Elperin and Vikhansky [Europhys. Lett. 42, 619 (1998)] and Makse [Phys. Rev. Lett. 83, 3186 (1999)] show good agreement at low Fr while that of Khakhar et al. [Phys. Fluids, 9, 31 (1997)] gives good predictions over the entire range of parameters considered. An analysis of the data indicate that the velocity gradient (gamma;) is nearly constant along the layer at low Fr, and the value calculated at the layer midpoint varies as gamma;(0)~[g sin(beta(0)-beta(s))/d cos beta(s)](1/2) for all the experimental data, where beta(s) is the static angle of repose and beta(0) is the interface angle at the layer midpoint. An extension of "heap" models (BCRE, BRdG) is used to predict the interface angle profiles, which are in reasonable agreement with experimental measurements.

Journal Article↗
PubMed2001

Psychomotor stimulant effects of beta-phenylethylamine in monkeys treated with MAO-B inhibitors.

RATIONALE AND OBJECTIVE: Sufficiently high doses of beta-phenylethylamine (beta-PEA), a trace amine that is rapidly metabolized by monoamine oxidase-type B (MAO-B), can produce effects comparable to those of cocaine or methamphetamine (MA). The present experiments were conducted to study how the discriminative-stimulus (S(D)) and reinforcing-stimulus (S(R)) effects of beta-PEA in monkeys are modified by treatment with inhibitors of MAO-B [R-(-)-deprenyl and MDL 72974]. METHODS AND RESULTS: In studies of its S(D) effects, doses of beta-PEA up to 30 mg/kg engendered only sporadic responding on the drug-associated lever in squirrel monkeys that discriminated intramuscular injections of 0.3 mg/kg MA from vehicle whereas lower doses of 0.3-1.0 mg/kg beta-PEA produced full substitution when administered after either R-(-)-deprenyl or MDL 72974 (0.3 mg/kg). The MA-like S(D) effects of beta-PEA were attenuated by either dopamine D(1) or D(2) receptor blockers. In studies of its S(R) effects, high doses of beta-PEA maintained responding in two of three monkeys under a second-order fixed-interval schedule (3.0 or 10 mg/kg per injection) and two of three monkeys under a simple fixed ratio (FR) schedule (0.3-1.0 mg/kg per injection) of intravenous (i.v.) self-administration. MAO-B inhibition by R-(-)-deprenyl or MDL 72974 enhanced the S(R) effects of beta-PEA in all monkeys and, under the FR schedule, induced a 30-fold or greater leftward shift in the dose-response function for its i.v. self-administration. Based on time-course determinations, the enhanced S(R) effects of beta-PEA under the FR schedule were long-lasting and dissipated gradually over 3-7 days. CONCLUSIONS: These results show that inhibition of MAO-B enhances S(D) and S(R) effects of beta-PEA in monkeys, presumably by delaying its inactivation. MAO-B inhibition leading to increased levels of beta-PEA may be useful, alone or in combination with other therapeutic agents, in the pharmacological management of selected aspects of drug dependence.

Animals↗
PubMed1975

Exercise responses following ozone exposure.

We have tested the response of 28 subjects to a three-stage ergometer test, with loads adjusted to 45, 60, and 75% of maximum aerobic power following ozone exposure. The subjects were exposed to one of 0.37, 0.50, or 0.75 ppm O3 for 2 h either at rest (R) or while exercising intermittently (IE) (15 min rest alternated with 15 min exercise at approximately 50 W. sufficient to increase VE by a factor of 2.5). Also, all subjects completed a mock exposure VE, respiratory frequency (fR), mixed expired PO2 and PCO2, and electrocardiogram were monitored continuously during the exercise test. Neither submaximal exercise oxygen consumption nor minute ventilation was significantly altered following any level of ozone exposure. The major response noted was an increase in respiratory frequency during exercise following ozone exposure. The increase in fR was closely correlated with the total dose of ozone (r = 0.98) and was accompanied by a decrease in tidal volume (r = 0.91) so that minute volume was unchanged. It is concluded that through its irritant properties, ozone modifies the normal ventilatory response to exercise, and that this effect is dose dependent.

Adult↗
PubMed1997

Antagonists for kinin B1 and B2 receptors in the mouse.

Contractile responses to B1 and B2 receptor agonists have been demonstrated in the mouse stomach; the mouse urinary bladder responds only to B2 receptor agonists. These tissues were used in this study to investigate the antagonistic effect of four B2 receptor antagonists, namely, DArg[Hyp3,DPhe7,Leu8]BK (BK, bradykinin), HOE-140, WIN 64338, and FR-173657 (B2 receptor antagonists), as well as three B1 kinin receptor antagonists; [Leu8]desArg9BK, Lys[Leu8]desArg9BK, and AcLys[D beta Nal7,Ile8]desArg9BK, were investigated. Results shown indicate that DArg[Hyp3,DPhe7,Leu8]BK is a partial agonist, while HOE-140 and FR-173657 are pure antagonists, devoid of direct myotropic effects, and quite selective for the B2 receptor. WIN 64338 was essentially inactive on both B1 and B2 receptors. The myotropic effect of DArg[Hyp3,DPhe7,Leu8]BK is blocked by HOE-140. Similarly, Lys[Leu8]desArg9BK and [Leu8]desArg9BK are B1 receptor partial agonists whose activities are blocked by AcLys[D beta Nal7,Ile8]desArg9BK (code name R 715), a fairly pure B1 receptor antagonist. Both HOE-140 and FR-173657 are long-acting, slowly reversible compounds that exert a noncompetitive type of antagonism, while R 715 is rapidly reversible and, thus, possibly competitive. Data presented in this paper provide a pharmacological characterization of B1 and B2 receptor antagonists in the mouse and underline the positive features of FR-173657 as a potent and selective B2 receptor antagonist, as well as the potency and purity of R 715 as a B1 receptor antagonist in the mouse.

Animals↗
PubMed2000

Magnetic information calibrates celestial cues during migration.

Migratory birds use celestial and geomagnetic directional information to orient on their way between breeding and wintering areas. Cue-conflict experiments involving these two orientation cue systems have shown that directional information can be transferred from one system to the other by calibration. We designed experiments with four species of North American songbirds to: (1) examine whether these species calibrate orientation information from one system to the other; and (2) determine whether there are species-specific differences in calibration. Migratory orientation was recorded with two different techniques, cage tests and free-flight release tests, during autumn migration. Cage tests at dusk in the local geomagnetic field revealed species-specific differences: red-eyed vireo, Vireo olivaceus, and northern waterthrush, Seiurus noveboracensis, selected seasonally appropriate southerly directions whereas indigo bunting, Passerina cyanea, and grey catbird, Dumetella carolinensis, oriented towards the sunset direction. When tested in deflected magnetic fields, vireos and waterthrushes responded by shifting their orientation according to the deflection of the magnetic field, but buntings and catbirds failed to show any response to the treatment. In release tests, all four species showed that they had recalibrated their star compass on the basis of the magnetic field they had just experienced in the cage tests. Since release tests were done in the local geomagnetic field it seems clear that once the migratory direction is determined, most likely during the twilight period, the birds use their recalibrated star compass for orientation at departure. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

The usefulness of celite-activated thromboelastography for evaluation of fibrinolysis.

PURPOSE: Although thromboelastography is useful for measuring both coagulability and fibrinolysis, it takes about two hours to measure all parameters including fibrinolytic rate. The present study aimed to investigate the usefulness of celite-activated thromboelastography (TEGc) to evaluate fibrinolytic status in non-cardiac surgery. METHODS: Whole blood samples were obtained from 30 patients for non-cardiac surgery, and used for measurements of both native TEG (TEGn) and TEGc. The final concentration of 1% (w/v) celite was used for TEGc. RESULTS: Time for measurement of the fibrinolytic rate (FR) of TEGc in patients (56.7 +/- 4.0 min) was less than half that of FR of TEGn (123.3 +/- 15.6 min) (P < 0.05), suggesting a more rapid assessment of fibrinolytic status. A linear relationship was observed between FR values of TEGc and those of TEGn (r = 0.93, P < 0.0001), suggesting the usefulness of the fibrinolytic parameter of TEGc. CONCLUSION: TEGc is a useful technique for a more rapid assessment of fibrinolytic status.

Adult↗
PubMed2025

TamL is a Key Player of the Outer Membrane Homeostasis in Bacteroidota.

In Proteobacteria, the outer membrane protein TamA and the inner membrane-anchored protein TamB form the Translocation and Assembly Module (TAM) complex, which facilitates the transport of autotransporters, virulence factors, and likely lipids across the two membranes. In Bacteroidota, TamA is replaced by TamL, a TamA-like lipoprotein with a lipid modification at its N-terminus that likely anchors it to the outer membrane. This structural difference suggests that TamL may have a distinct function compared to TamA. However, the role of TAM in bacterial phyla other than Proteobacteria remains unexplored. Our study aimed to elucidate the function of TamL in Flavobacterium johnsoniae, an environmental Bacteroidota. Unlike its homologs in Proteobacteria, we found that TamL and TamB are essential in F. johnsoniae. Through genetic, phenotypic, proteomic, and lipidomic analyses, we show that TamL depletion severely compromises outer membrane integrity, as evidenced by reduced cell viability, altered cell shape, increased susceptibility to membrane-disrupting agents, and elevated levels of outer membrane lipoproteins. Notably, we did not observe an overall decrease in the levels of &#x3b2;-barrel outer membrane proteins, nor substantial alterations in outer membrane lipid composition. By pull-down assays, we found TamL co-purifying with TamB in F. johnsoniae, suggesting an interaction. Furthermore, we found that while TamL and TamB monocistronic genes are conserved among Bacteroidota, only some species encode multiple TamL, TamB and TamA proteins. To our knowledge, this study is the first to provide functional insights into a TAM subunit beyond Proteobacteria.

Bacterial Outer Membrane Proteins↗
PubMed2005

[Efficacy of Derinox assessed with one PNIF (Peak Nasal Inspiratory Flow) in patients suffering from common cold].

OBJECTIVES: The aim of this study was to compare the efficacy and tolerance of Dérinox (D) to Rhinofluimucil (R) and placebo (P) in the treatment of common cold, using an objective measure of nasal obstruction, the Peak Nasal Inspiratory Flow (PNIF--Clement Clarke International, Harlow, Angleterre). PATIENTS AND METHODS: This randomized, double-blind, double-dummy, parallel group study enrolled 354 patients (34 P, 165 D et 155 R) included by 85 general practitioners. The treatment duration was 5 days at usual recommended dosage regimens. PNIF measures were done before drug administration (T0) as well as 15 min and 3 h after each intake. Moreover, nasal obstruction, rhinorrhea and global discomfort were subjectively assessed. RESULTS: The efficacy of D was superior to that of P and R when comparing PNIF from T0 to T3 h after the first intake. At T15 min, rhinorrhea was significantly improved with both active treatments and global discomfort was significantly improved with D only. Treatment tolerance was satisfactory and comparable between the 3 groups. CONCLUSION: Efficacy of Dérinox(R) was superior to that of P and R for the improvement of the nasal obstruction (PNIF) between T0 and T3h (main criteria) after the first intake in patients suffering from common cold.

Acetylcysteine↗
PubMed1980

[rC.B.F. measurements by a gamma camera and the 133 Xe inhalation technique. Interest of a local partition coefficient tissue-blood (author's transl)].

More than 400 patients who had undergone a cerebrovascular attack or a transitory ischemic attack had bilateral measurements of regional C.B.F. by the 133 Xe inhalation technique and a gamma-camera. Inhalation of the air-Xe mixture in the closed spirometric circuit takes 1.5 mn at a concentration of 1 to 2 mCi/1. A very high resolution collimator allows a maximal counting rate of 300 000 i.p.m per hemisphere. At the opening of the circuit, the cerebral curves are analysed by the initial slope index (ISI) method, that index being obtained by deconvolution of the first 2.5 minutes of wash out. With this method, normal values are: 44,5 +/- 5ml/mn/100g. After calculation of hemispheric and regional ISI, we evaluate a regional partition coefficient (for total hemisphére) between tissue and blood with this formula: Formula: [See Text], being the activities counted at time t respectively in the area and on the hemisphere. Koh and Kor referring to ISI in total hemisphere (H) and area (r) C (a): arterial concentration A regional blood flow is obtained by Fr = 100 lambda rKor in a maximum of 16 different areas (with lambda n = 1ml/g) With our data processing system we get a functional image of r CBF which visualizes values of the (lambda r. Kor). In order to avoid statistical problems due to separate calculations of lambda r and Kor in very small areas we use a very simple kind of a functional image: subtraction of regional cerebral activity between time 0.5 and 1.5 mn and at 1.5 and 2.5 mn of wash out. We show that this image is correct display of regional inequalities of lambda rKor. In 48 cases of complete stroke comparison of the ISI index Kor and the ISI index Kor and the lambda r Kor referring to the area of maximal ischemia appearing on the functional image showed perfect correlation between the lambda rKor and the functional image; and only in 80% cases with the unique value of Kor. Those discrepancies between Kor and lambda rKor are related to necrosis and late revascularisation in cerebro vascular attacks.

Cerebrovascular Circulation↗
PubMed1995

Differential effects of dopamine D1 and D2 receptor agonists on schedule-controlled behavior of squirrel monkeys.

The effects of dopamine agonists differing in affinity and selectivity at D1 and D2 types of dopamine receptors were compared in squirrel monkeys responding under two different schedules of reinforcement: a fixed-interval (FI) schedule of stimulus-shock termination and a fixed-ratio (FR) schedule of food presentation. Dopamine D1 family agonists included dihydrexidine, SKF 81297, SKF 82958, R-6-Br-APB, SKF 83189, SKF 77434, SKF 75670 and R- and R, S-SKF 38393. Dopamine D2 agonists included (+)-PHNO, quinpirole and N-0434; nonselective DA agonists included R(-)-apomorphine and CY 208-243. The behavioral effects of D1 agonists differed qualitatively from those of D2 and nonselective DA agonists. D1 agonists produced dose-related decreases in both FI and FR responding, with comparable doses being effective under the two schedules. The rank order of potency for the rate-decreasing effects of these drugs was R(+)-6-Br-APB > SKF 75670 > SKF 82958 > R-SKF 38393 > SKF 81297 > SKF 77434 > SKF 83189 > dihydrexidine > R, S-SKF 38393. In contrast, D2 and nonselective DA agonists produced significant increases in rates of FI responding at doses that reduced FR response rates. The rank order of potency for the rate-increasing effects of these drugs under the FI schedule was (+)-PHNO > N-0434 > R-apomorphine > CY 208-243 > quinpirole.(ABSTRACT TRUNCATED AT 250 WORDS)

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1987

Behavioral and cardiovascular effects of analogs of adenosine in cynomolgus monkeys.

The behavioral and cardiovascular effects of six metabolically stable analogs of adenosine were studied in cynomolgus monkeys. Behavioral effects were determined in monkeys trained to respond under a 30-response fixed-ratio (FR) schedule of food presentation; cardiovascular effects were evaluated in a separate group of unanaesthetized monkeys seated at rest. Dose-effect curves for each drug were determined by administering cumulative doses i.v. during sequential components of the experimental session. All six analogs of adenosine produced dose-related decreases in FR responding with the following order of potency: 5'N-ethylcarboxamide adenosine (NECA) greater than 2-chloroadenosine (2-CA) greater than N6-R-phenylisopropyladenosine (R-PIA) greater than N6-cyclopentyladenosine (CPA) greater than N6-cyclohexyladenosine (CHA) greater than N6-S-phenylisopropyladenosine (S-PIA). In cardiovascular studies, all drugs except CPA produced dose-related decreases in mean blood pressure (MBP) with the following order of potency: NECA greater than 2-CA = R-PIA greater than CHA greater than S-PIA. CPA did not alter MBP at doses that decreased both FR responding and heart rate (HR). All drugs except NECA produced dose-related decreases in HR with the following order of potency: CPA greater than 2-CA greater than R-PIA greater than CHA greater than S-PIA. NECA increased HR at doses that decreased MPB and FR responding. Doses of caffeine that did not alter FR responding or cardiovascular function when given alone antagonized the behavioral effects of R-PIA, CHA, CPA and NECA. Caffeine also antagonized the effects of R-PIA, CHA and NECA on MBP and the effects of R-PIA and CPA on HR.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Chloroadenosine↗