Assessment of clonidine effect as premedicative drug on kidney function.

OBJECTIVE: To assess the effect of oral clonidine as a premedicative drug on 24-hour urine output, urine specific gravity, plasma renin activity as well as serum and urine electrolytes levels. METHODS: This prospective study was carried out on 60 women aged 20-40 years old undergoing repair of cystocoele-rectocoele perineorraphy under general anaesthesia in Asali Hospital in 2004 in Khorramabad, Iran. Subjects were randomly divided into two equal groups of 30 each. Group I and group II received clonidine tablet at the dose of 5 microg/kg and placebo tablet, respectively, 90 minutes before induction of general anesthesia. In this study, blood and urine samples were taken for laboratory measurements prior as well as 6 hours after taking the tablets. Differences between the two groups were compared through Mann-Whitney u-test, chi2 test and t-student test. P-value < 0.05 was considered statistically significant. RESULTS: There were no significant changes before and after receiving tablets in urine and blood Na and K as well as urine specific gravity in group II (P > 0.05). Group I had higher urine Na and K level (P = 0.001), however, no differences had been shown in blood Na and K level (P > 0.05). Urine specific gravity was lower in group I after receiving tablet (P < 0.009). A significant increase in 24-hour urine output (P = 0.001) and a marked decrease in plasma renin activity was seen in group I (P = 0.001). CONCLUSION: This study suggests that clonidine is a safe premedicative drug in anaesthesia and does not change the serum electrolytes levels.

Attenuation of hemodynamic responses following laryngoscopy and tracheal intubation -- comparative assessment of clonidine and gabapentin premedication.

OBJECTIVE: The present study was conducted to compare the effect of clonidine and gabapentin premedication in modifying the hyperdynamic response following laryngoscopy and tracheal intubation. METHODS AND MATERIALS: Seventy-five ASA I-II patients of both sexes (37 males (49.3%), 38 females (50.7%)) 18 to 45 years (mean 32.8 +/- 8.65 yr.) were randomly allocated into three equal groups (25 each). Group-1 received 0.2 mg clonidine, Group-2 received placebo and Group-3 received 900 mg gabapentin, 120 minute before operation. Heart rate, systolic, diastolic and mean arterial blood pressure were measured before induction of anesthesia, before laryngoscopy, and 1, 3, 5, 10 min after intubation. RESULTS: Analysis revealed that the heart rate, systolic, diastolic and mean arterial blood pressure significantly differed between groups (p<0.001, p = 0.003, p<0.001, p<0.001, respectively). The highest rates of heart rate, systolic, diastolic and mean arterial blood pressure were in the placebo group and in one minute after laryngoscopy, and the lowest rate were in the gabapentin group at the time of 1, 3, 5 and 10 after laryngoscopy, except that the lowest rate of heart rate in 10 min after laryngoscopy was in clonidine group. CONCLUSION: The data propose that both clonidine and gabapentin have effective role in blunting hyperdynamic responses after laryngoscopy, more so with gabapentin.

Assessment of serum enzymatic markers of cardiomyocytes injury in female dogs submitted to ketamine S(+), atropin and xylazine association / Mensuração da atividade sérica de marcadores de lesão cardíaca em cadelas anestesiadas com cetamina S(+), atropina e xilazina

PURPOSE: To assessment of the aspartate aminotransferase (AST), creatine kinase (CK) and creatine kinase isoenzyme fraction MB (CK-MB) serum activity in female dogs anesthetized with ketamine S (+), atropine and xylazine in several associations. METHODS: Twenty three healthy female dogs randomly distributed in four groups named as GI (n=6), GII (n=6), GIII (n=6) and GIV (n=5) were treated respectively with atropine and ketamine S(+) (0.04mg/kg; 10 mg/kg); ketamine S(+) (10 mg/kg); atropine, xylazine and ketamine S(+) (0.04mg/kg; 1.1 mg/kg; 10 mg/kg) and xylazine and ketamine S(+) (1.1 mg/kg; 10 mg/kg). AST, CK and CK-MB serum activity measurement before pre-medication (M0) and one, two, three, six, 12, 24, 36 hours after. RESULTS: There was no significant change in AST, CK e CK-MB serum activity among groups. However, CK serum activity in relation to moments within the groups was increased in all groups over the time in spite of treatment, except GI. In relation to CK-MB activity, in the moments within the group, it was observed an increase compared to baseline in all groups. CONCLUSION: Creatine kinase and creatine kinase fraction MB isoenzyme showed changes in their mean values remained higher than baseline for a longer time in GIII and GIV.

OBJETIVO: Determinar a atividade sérica de AST, CK e CK-MB em cadelas anestesiadas com cetamina S (+), atropina e xilazina em diferentes associações. MÉTODOS: Vinte e três cadelas saudáveis foram distribuídas ao acaso em quarto grupos denominados GI (n=6), GII (n=6), GIII (n=6) e GIV (n=5) tratados respectivamente com atropina e cetamina S (+) (0,04mg/kg; 10 mg/kg); cetamina S (+) (10 mg/kg); atropina, xilazina e cetamina S (+) (0,04mg/kg; 1,1 mg/kg; 10 mg/kg) exilazina e cetamina S (+) (1,1 mg/kg; 10 mg/kg). A atividade sérica de AST, CK e CK-MB foi determinada antes da pré-medicação (M0) e uma, duas, três seis, 12, 24 e 36 horas após M0. RESULTADOS: Não foram encontradas mudanças significativas na atividade sérica de AST, CK e CK-MB entre grupos. Entretanto, entre momentos houve aumento da atividade sérica de CK para todos os grupos, exceto em GI.Com relação a atividade sérica de CK-MB, observou-se ao longo dos momentos aumento significativo com relação aos valores basais em ambos os grupos. CONCLUSÃO: Alterações significativas foram observadas com relação à atividade sérica de CK e CK-MB em todos os tratamentos, mantendo-se elevada por um período maior nos grupos GIII e GIV.

Assessment of serum enzymatic markers of cardiomyocytes injury in female dogs submitted to ketamine S(+), atropin and xylazine association.

PURPOSE: To assessment of the aspartate aminotransferase (AST), creatine kinase (CK) and creatine kinase isoenzyme fraction MB (CK-MB) serum activity in female dogs anesthetized with ketamine S (+), atropine and xylazine in several associations. METHODS: Twenty three healthy female dogs randomly distributed in four groups named as GI (n=6), GII (n=6), GIII (n=6) and GIV (n=5) were treated respectively with atropine and ketamine S(+) (0.04 mg/kg; 10 mg/kg); ketamine S(+) (10 mg/kg); atropine, xylazine and ketamine S(+) (0.04 mg/kg; 1.1 mg/kg; 10 mg/kg) and xylazine and ketamine S(+) (1.1 mg/kg; 10 mg/kg). AST, CK and CK-MB serum activity measurement before pre-medication (M0) and one, two, three, six, 12, 24, 36 hours after. RESULTS: There was no significant change in AST, CK e CK-MB serum activity among groups. However, CK serum activity in relation to moments within the groups was increased in all groups over the time in spite of treatment, except GI. In relation to CK-MB activity, in the moments within the group, it was observed an increase compared to baseline in all groups. CONCLUSION: Creatine kinase and creatine kinase fraction MB isoenzyme showed changes in their mean values remained higher than baseline for a longer time in GIII and GIV.

Silodosin: a selective alpha1A-adrenergic receptor antagonist for the treatment of benign prostatic hyperplasia.

BACKGROUND: Silodosin is a new alpha(1)-adrenergic receptor antagonist that is selective for the alpha(1A)-adrenergic receptor. It was approved by the US Food and Drug Administration (FDA) in 2008 for the treatment of lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH). OBJECTIVE: This article reviews the pharmacology, pharmacokinetics, clinical efficacy, adverse effects, drug interactions, and dosage and administration of silodosin in adult male patients with BPH. METHODS: A search of MEDLINE (1950-October 8, 2009), International Pharmaceutical Abstracts (1970-October 8, 2009), and the Iowa Drug Information Service database (1966-October 8, 2009) was conducted using the terms silodosin, KMD-3213, benign prostatic hyperplasia, and alpha(1)-adrenergic receptor antagonist. Reports of research and review articles published in English were identified and evaluated, and the bibliographies of these articles were reviewed for additional relevant publications. A search of the FDA Web site was performed, and abstracts and posters presented at scientific meetings of the American Urological Association were reviewed. RESULTS: By antagonizing alpha(1A)-adrenergic receptors in the prostate and urethra, silodosin causes smooth muscle relaxation in the LUT. Silodosin has greater affinity for the alpha(1A)-adrenergic receptor than for the alpha(1B)-adrenergic receptor (by a factor of 583), minimizing the propensity for blood pressure-related adverse effects mediated by alpha(1B) blockade. In 3 controlled clinical studies in patients with BPH-related LUTS (1 published; 2 presented in the prescribing information and published in a pooled analysis), patients receiving silodosin at a total daily dose of 8 mg had significant improvements in the International Prostate Symptom Score (IPSS) and maximum urinary flow rate (Q(max)) compared with those receiving placebo (both, P < 0.05). The most commonly reported adverse effect was abnormal or retrograde ejaculation (>22%), and the incidence of orthostatic hypotension was low (<3%). CONCLUSIONS: In the small number of clinical trials reviewed, silodosin was associated with significant reductions in IPSS and Q(max) compared with placebo. To determine whether silodosin's selectivity for the alpha(1A)-adrenergic receptor translates into a clinical advantage relative to other available agents, long-term studies evaluating the comparative efficacy and tolerability of silodosin and other alpha(1)-blockers (specifically tamsulosin) are necessary.

Use of multichannel electrointestinography for noninvasive assessment of myoelectrical activity in the cecum and large colon of horses.

OBJECTIVE: To evaluate whether changes in myoelectrical activity in the cecum and large colon of horses can be detected via multichannel electrointestinography (EIG). ANIMALS: 6 healthy mature horses. PROCEDURES: Each horse underwent 3 EIG procedures. Intestinal myoelectrical activity (cecum and large colon) was recorded during a 20-minute period following i.v. administration of physiologic saline (0.9% NaCl) solution (20 mL; baseline), erythromycin lactobionate (0.5 mg/kg), or detomidine (0.015 mg/kg); intestinal contractions were concurrently viewed via B-mode ultrasonography. By use of computer software, 8-channel EIG recordings were analyzed and the mean of the dominant frequency (a measure of the rhythmicity of gastric electrical activity) expressed in cycles per minute (cpm) was obtained. Total power (muV(2)) was calculated, and treatment effect was expressed as the power ratio (ie, treatment-associated power divided by the baseline power). RESULTS: The dominant frequency cpm values were not stable, and no significant differences between treatments were detected. Compared with the effects of saline solution treatment, detomidine significantly reduced the mean cecal and colonic power ratios. Erythromycin significantly reduced the cecal power ratio and increased the colonic power ratio, although the increase was significant in only 1 channel. Ultrasonographic findings and total power (predominantly from the long-distance electrode pairs) were significantly correlated. CONCLUSIONS AND CLINICAL RELEVANCE: In horses, EIG was useful for assessment of changes in myoelectrical activity in the cecum and large colon. Multiple electrodes should be used to cover a larger area of the intestine, and agreement between multiple channels is needed to make the analysis meaningful.

An assessment of the role of reactive oxygen species and redox signaling in norepinephrine-induced apoptosis and hypertrophy of H9c2 cardiac myoblasts.

Cardiac myocytes, upon exposure to increasing doses of norepinephrine (NE), transit from hypertrophic to apoptotic phenotype. Since reactive oxygen species (ROS) generation is attributed to both phenomena, the authors tested whether an elevation in intracellular ROS level causes such transition. H9c2 cardiac myoblasts upon treatment with hypertrophic and apoptotic doses of NE (2 and 100 microM, respectively) transiently induced intracellular ROS at a comparable level, while 200 microM H(2)O(2), another proapoptotic agonist, showed robust and sustained ROS generation. Upon analysis of a number of redox-responsive transcription factors as the downstream targets of ROS signaling, the authors observed that NE (2 and 100 microM) and H(2)O(2) (200 microM) were ineffective in inducing NF-kappaB while both the agonists upregulated AP-1 and Nrf-2. However, the extents of induction of AP-1 and Nrf-2 were not in direct correlation with the respective ROS levels. Also, AP-1 activities induced by two doses of NE were intrinsically different, since at 2 microM, it primarily induced FosB, and at 100 microM it activated Fra-1. Differential induction of FosB and Fra-1 was also reiterated in adult rat myocardium injected with increasing doses of NE. Therefore, NE induces hypertrophy and apoptosis in cardiac myocytes by distinct redox-signaling rather than a general surge of ROS.

[Analysis of heart rate variability in assessment of baroreflex sensitivity in anesthetized rats].

Spectral analysis of the heart rate variability can be used as a measure of baroreflex sensitivity in ketamine anesthetized rats. Stimulation of delta1-receptors with phenylephrine (0.01 mg/kg, i.v.) results in a rise of the strength of heart rate regulation, principally in the low frequency band. Maximal deviations of spectral indexes from basal level were observed on 4-8 min for low (0.2-1 Hz) and high (1-3 Hz) frequencies bands and on 10-15 min for very low (0.08-0.2 Hz) frequency band after phenylephrine injection.

Spontaneous baroreflex measurement in the assessment of cardiac vagal control.

Spontaneous baroreflex sensitivity (SBR) has been suggested to be a measure of tonic parasympathetic cardiac control. The decrease of SBR during vagal inhibition was proven before. In this study, we investigated the response of SBR during vagal activation by administering intravenous atropine and phenylephrine in eight and ten healthy volunteers respectively. Atropine was given at a rate of 0.5 micro g/kg/min for 20 minutes and the infusion rate of phenylephrine was adjusted to increase the blood pressure 20 to 30 mmHg above baseline value. We found that SBR at first increased from 16.9 +/- 9.5 to 41.5 +/- 24.9 ms/mm Hg (p < 0.05) and then decreased to 8.9 +/- 6.2 ms/mm Hg (p < 0.05 compared with the peak value) after the initiation of atropine infusion. SBR also increased significantly (27.2 +/- 12.5 to 49.6 +/- 11.3 ms/mm Hg, p < 0.01) during phenylephrine infusion. The authors propose SBR as a measure of cardiac vagal effect because SBR increases under vagal activation.

Assessment of anti-migraine potential of a novel alpha-adrenoceptor agonist S19014: effects on porcine carotid and regional haemodynamics and human coronary artery.

Taking into account the drawbacks associated with the use of triptans, attempts are being made to explore other avenues for the treatment of migraine. Recently, it has been shown that both alpha1- and alpha2-adrenoceptors mediate the constriction of porcine carotid arteriovenous anastomoses, which has effectively served as an experimental model predictive of anti-migraine activity. The present study investigated the effects of a novel alpha-adrenoceptor agonist S19014 (spiro[(1,3-diazacyclopent-1-ene)-5 : 2'-(4',5'-dimethylindane)] fumarate) on carotid and systemic haemodynamics in anaesthetized pigs, and on human isolated coronary arteries. Increasing doses of S19014 (1-30 micro g/kg, i.v.) produced a dose-dependent initial short-lasting vasopressor response and a decrease of total carotid blood flow and conductance. The carotid blood flow and conductance changes were exclusively due to constriction of carotid arteriovenous anastomoses (capillary blood flow increased) and were accompanied by an increase in arterio-jugular venous oxygen saturation difference. Whereas prazosin (100 micro g/kg, i.v.) was ineffective, rauwolscine (300 micro g/kg, i.v.) attenuated the responses to S19014. The compound did not much affect the distribution of cardiac output to peripheral organs when compared with the vehicle group. Furthermore, S19014 only slightly contracted the human isolated coronary artery and its contractions, contrary to those of sumatriptan, were not increased in blood vessels pre-contracted with U46619. These results suggest that (i) the systemic and carotid vascular effects of S19014 are mainly mediated by alpha2-adrenoceptors, and (ii) S19014 could be effective in the treatment of migraine with an improved cardiovascular tolerance.

Noninvasive assessment of gastric emptying by near-infrared fluorescence reflectance imaging in mice: pharmacological validation with tegaserod, cisapride, and clonidine.

Noninvasive near-infrared fluorescence reflectance imaging (FRI) is an in vivo technique to assess physiological and molecular processes in the intact organism. Here we describe a method to assess gastric emptying in mice. TentaGel beads with covalently bound cyanine dye (Cy5.5) conjugates as fluorescent probe were administered by oral gavage. The amount of intragastric beads/label was derived from the fluorescence signal intensity measured in a region of interest corresponding to the mouse stomach. The FRI signal intensity decreased as a function of time reflecting gastric emptying. In control mice, the gastric half-emptying time was in agreement with literature data. Pharmacological modulation of gastric motility allowed the evaluation of the sensitivity of the FRI-based method. Gastric emptying was either stimulated or inhibited by treatment with the 5-HT(4) receptor agonists tegaserod (Zelnorm) and cisapride or the alpha(2)-receptor agonist clonidine, respectively. Tegaserod and cisapride dose-dependently accelerated gastric emptying. In contrast, clonidine dose-dependently delayed gastric emptying. In conclusion, FRI using fluorescently labeled beads allows the reliable determination of gastric emptying as well as the assessment of pharmacological interventions. The technique thus offers the potential to characterize molecular targets and pathways involved in physiological regulation and pharmacological modulation of gastric emptying.

In vivo assessment of the regulatory mechanism of cholinergic neuronal activity associated with motility in dog small intestine.

Intestinal motor activity associated with acetylcholine (ACh) release was assessed in the small intestine of anesthetized dogs by simultaneous measurement of motor activity and local ACh concentrations within the intestinal wall with in vivo microdialysis. Basal concentration of ACh measured in the dialysate was 1.12 +/- 0.08 pmol/15 min (n = 10), a value that remained constant until 3 h after perfusion. Intra-arterial infusion of tetrodotoxin reduced dialysate ACh concentration, while the motor activity accelerated at the early phase after infusion of tetrodotoxin and then decreased, thereby suggesting that the motor activity is regulated by not only excitatory cholinergic neurons, but also inhibitory neurons. Intraarterial infusion of atropine increased dialysate ACh concentration but reduced motor activity, thereby indicating that the cholinergic neurons are tonically active and the muscarinic autoreceptors operate to inhibit the ACh release. Intraarterial infusion of norepinephrine reduced, but yohimbine increased both motor activity and dialysate ACh concentration, thereby indicating that the adrenergic neurons regulate the motor activity due to control of cholinergic neuronal activity. This in vivo microdialysis method demonstrated in the whole body of animals that the activity of cholinergic neurons was physiologically regulated by itself and adrenergic neurons.

Dexmedetomidine--a novel sedative for postoperative sedation.

Dexmedetomidine is new sedative being developed for use in postoperative sedation in ICU. It acts at a 2 adrenoceptors to produce sedation, anxiolysis and analgesia. Patients remain easily rousable and do not suffer significant respiratory depression, consequently dexmedetomidine may be continued post extubation.

Pharmacological assessment of adrenergic receptors in human varicose veins.

BACKGROUND: Experiments were to characterize pharmacologically adrenergic receptors in human varicose veins to the natural transmitter norepinephrine and to an extract of Ruscus. METHODS: Greater saphenous veins and varicose tributaries from patients undergoing elective surgery for primary varicose disease and portions of greater saphenous veins from patients undergoing peripheral arterial reconstruction (control) were suspended for the measurement of isometric force in organ chambers. Concentration response curves were obtained to norepinephrine or the extract of Ruscus aculeatus in the absence and presence of selective antagonists of alpha, and alpha2 adrenergic receptors. RESULTS: Norepinephrine and Ruscus extract caused concentration-dependent contractions in all veins. Contractions to norepinephrine were greater in control veins than in varicose tributaries. Contractions to the extract were greater in varicose tributaries than in greater saphenous veins from varicose patients. Contractions to norepinephrine were reduced similarly by alpha and alpha2-adrenergic agonists in control and varicose veins but to a greater extent by alpha2-blockade in greater saphenous veins from varicose patients. Contractions to Ruscus extract were not reduced by alpha-adrenergic blockade in control veins but were reduced by alpha2-adrenergic blockade in varicose veins. CONCLUSIONS: These results suggest a differential distribution of alpha adrenergic receptors on greater saphenous veins from non-varicose patients compared to those with primary varicose disease. Venotropic agents from plant extract probably exert effects by way of multiple receptor and non-receptor mediated events.

Physiological, pharmacological and neurohormonal assessment of autonomic function in progressive supranuclear palsy.

The clinical features of progressive supranuclear palsy (PSP) overlap with other parkinsonian syndromes, including multiple system atrophy (MSA). Autonomic dysfunction is a characteristic of MSA, but has also been described in PSP. We therefore report results from a series of physiological studies of cardiovascular autonomic function in 35 PSP and 20 MSA subjects, and 26 age-matched healthy control subjects. The response to growth hormone-clonidine testing, a neuropharmacological assessment of central adrenoceptor function, was also assessed in 14 PSP and 10 MSA subjects, and compared with 10 controls. None was on medication which may have affected the results. Orthostatic hypotension did not occur in PSP subjects or controls, unlike MSA subjects. Overall there was no evidence of sympathetic vasoconstrictor failure in PSP subjects, unlike MSA subjects, although the pressor response to mental arithmetic was reduced. Cardiac parasympathetic function was affected in only a minority (three of 35) of PSP subjects and was abnormal in MSA subjects. After clonidine administration, growth hormone rose in PSP subjects (median increase 4.3; interquartile range 1.8-7.8 mU/l) and controls, unlike MSA subjects (0.9; 0.3-2.4 mU/l; P < 0.005, Mann-Whitney U-test). In conclusion, in PSP subjects, responses to both physiological and pharmacological tests provided evidence against widespread autonomic dysfunction; this differed markedly from MSA subjects. Thus, cardiovascular autonomic dysfunction should be an exclusionary feature in the diagnosis of PSP.

2-amino-2-oxazolines as subtype selective alpha(2) adrenoceptor agonists.

Cyclohexylamino oxazoline 1 (AGN 190837), an analogue of 2 (Bay a6781), is a potent alpha(2) adrenoceptor agonist. On the basis of a design generated by receptor-ligand modeling, a number of cyclohexyl and norbornyl analogues were synthesized wherein the propyl group of 1 was replaced by phenylalkyl subsituents. This resulted in compound 6 being an alpha(2c) selective agonist, as well as 7 and 9 being alpha(2a)/alpha(2c) selective.

Functional assessment of recombinant human alpha(2)-adrenoceptor subtypes with cytosensor microphysiometry.

We applied the Cytosensor Microphysiometry system to study the three human alpha(2)-adrenoceptor subtypes, alpha(2A), alpha(2B) and alpha(2C), expressed in Chinese hamster ovary (CHO) cells, and assessed its potential in the quantitative monitoring of agonist activity. The natural full agonist, (-)-noradrenaline, was used to define agonist efficacy. The imidazole derivative dexmedetomidine was a potent full agonist of all three receptor subtypes. The imidazolines clonidine and UK 14,304 (5-bromo-N-(4, 5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine) appeared to be partial agonists at alpha(2B)-adrenoceptors (E(max) approximately 60% of (-)-noradrenaline) but full agonists at alpha(2A)- and alpha(2C)-adrenoceptors. The responses mediated by all three alpha(2)-adrenoceptor subtypes were partly inhibited by the sodium-hydrogen (Na(+)/H(+)) exchange inhibitor, MIA (5-(N-methyl-N-isobutyl)-amiloride). The agonist responses were totally abolished by pretreatment with pertussis toxin in cells with alpha(2A)- and alpha(2C)-adrenoceptors, and partly abolished in cells with alpha(2B)-adrenoceptors. The residual signal in alpha(2B)-cells was sensitive to the intracellular Ca(2+)chelator, BAPTA (1,2-bis(2-aminophenoxy)ethane-N,N,N,N-tetraacetic acid acetoxymethyl ester). Cholera toxin (which acts on G(s)-proteins) had no effect on the agonist responses. The results suggest that the extracellular acidification responses mediated by all three human alpha(2)-adrenoceptor subtypes are dependent on Na(+)/H(+)exchange and G(i/o) pathways, and that alpha(2B)-adrenoceptors are capable of coupling to another, G(i/o)-independent and Ca(2+)-dependent signaling pathway.