Inhibition of insulin secretion from rat pancreatic islets by dexmedetomidine and medetomidine, two sedatives frequently used in clinical settings

Dexmedetomidine suppresses glucose-stimulated insulin secretion in pancreatic β-cells

Proper glycemic control is crucial for patient management in critical care, including perioperative care, and can influence patient prognosis. Blood glucose concentration determines insulin secretion and sensitivity and affects the intricate balance between the glucose metabolism. Human and other animal studies have demonstrated that perioperative drugs, including volatile anesthetics and intravenous anesthetics, affect glucose-stimulated insulin secretion (GSIS). Dexmedetomidine (DEX) decreases insulin release and affects glucose metabolism; however, the specific mechanism underlying this phenomenon remains largely unknown. Thus, we investigated the effect and mechanism of DEX on insulin secretion using mouse and rat pancreatic β-cell-derived MIN6 and INS-1 cell lines and primary pancreatic β-cells/islets extracted from mice. The amount of insulin secreted into the culture medium was determined using an enzyme-linked immunosorbent assay. Cell viability, cytotoxicity, and electrophysiological effects were investigated. Clinically relevant doses of DEX suppressed GSIS in MIN6 cells, INS-1 cells, and pancreatic β-cells/islets. Furthermore, DEX suppressed insulin secretion facilitated by insulinotropic factors. There was no significant difference in oxygen consumption rate, intracellular ATP levels, or caspase-3/7 activity. Electrophysiological evaluation using the patch-clamp method showed that DEX did not affect ATP-sensitive potassium (KATP) channels, voltage-dependent potassium channels, or voltage-gated calcium channels. We demonstrated that clinically relevant doses of DEX significantly suppressed GSIS. These findings suggest that DEX inhibits a signaling pathway via α2-adrenoceptor or insulin vesicle exocytosis, resulting in GSIS suppression. Our results support the hypothesis that DEX suppresses insulin secretion and reveal some underlying mechanisms.

The Effect of a Subsequent Dose of Dexmedetomidine or Other Sedatives following an Initial Dose of Dexmedetomidine on Electrolytes, Acid-Base Balance, Creatinine, Glucose, and Cardiac Troponin I in Cats: Part II

The administered dose of dexmedetomidine may occasionally fail to produce the anticipated sedative effects. Therefore, a subsequent dose or administration of another sedative may enhance sedation; however, patient safety may be affected. The safety of seven different drugs administered at the following time point after an insufficient dose of dexmedetomidine was evaluated in a crossover, blind, experimental study that included six healthy adult cats. All cats received an initial dose of dexmedetomidine and a subsequent dose of either dexmedetomidine (Group DD), NS 0.9% (DC), tramadol (DT), butorphanol (DBT), buprenorphine (DBP), ketamine (DK), or midazolam (DM). Animal safety was assessed using repeated blood gas analysis and measurement of electrolytes, glucose, cardiac troponin I, and creatinine to evaluate cardiac, respiratory, and renal function. The median values of creatinine, cardiac troponin I, pH, partial pressure of carbon dioxide, potassium, and sodium did not change significantly throughout the study. Heart rate was significantly decreased in all groups after administration of the drug combinations, except for in the DK group. Respiratory rate decreased significantly after administration of the initial dose of dexmedetomidine and in the DBP and DM groups. The partial pressure of oxygen, although normal, decreased significantly after the administration of dexmedetomidine, whereas the median concentration of glucose increased significantly following the administration of dexmedetomidine. The results of our study suggest that the drug combinations used did not alter the blood parameters above normal limits, while cardiac and renal function were not compromised. Therefore, a safe level of sedation was achieved. However, the administration of dexmedetomidine reduced the partial pressure of oxygen; thus, oxygen supplementation during sedation may be advantageous. Additionally, the increase in glucose concentration indicates that dexmedetomidine should not be used in cats with hyperglycaemia, whereas the decrease in haematocrit suggests that dexmedetomidine is not recommended in anaemic cats.

Case report: Low dose dexmedetomidine infusion for the management of hypoglycemia in a dog with an insulinoma

Objective

To describe the use of a low dose dexmedetomidine infusion as preoperative treatment for hypoglycemia secondary to a functional pancreatic tumor in a dog.

Case summary

An 8.7-year-old castrated male Hungarian Vizsla presented for further evaluation of persistent hypoglycemia after the referring veterinarian established a tentative diagnosis of insulinoma based on paired insulin and glucose measurements. Abdominal ultrasound and computed tomography demonstrated evidence of a pancreatic mass with possible hepatic metastases. Attempts to aspirate the lesions under ultrasound guidance were unsuccessful, and the dog was hospitalized overnight for planned surgical resection of the presumed pancreatic tumor and biopsy of the hepatic lesions the following day. In response to a progressive increase in patient anxiety and agitation trazodone was prescribed ~5 mg/kg orally every 8 h and gabapentin at ~7 mg/kg every 8 h. As the dog continued to remain anxious dexmedetomidine at a dose of 1 mcg/kg was administered intravenously immediately followed with an infusion of dexmedetomidine at 1 mcg/kg/h. The anxious behaviors were successfully controlled with minimal cardiovascular side effects. Serial blood glucose measurements obtained during this time demonstrated euglycemia. The dog remained euglycemic while receiving dexmedetomidine for the remainder of the pre-operative period and for duration of hospitalization following surgical resection and biopsy.

New or unique information provided

This case report demonstrates a possible role for dexmedetomidine to counteract hypoglycemia in dogs with insulinomas.

Choice of anesthesia and data analysis method strongly increases sensitivity of 18F-FDG PET imaging during experimental epileptogenesis

Purpose

Alterations in brain glucose metabolism detected by 2-deoxy-2-[¹⁸F]-fluoro-D-glucose (¹⁸F-FDG) positron emission tomography (PET) may serve as an early predictive biomarker and treatment target for epileptogenesis. Here, we aimed to investigate changes in cerebral glucose metabolism before induction of epileptogenesis, during epileptogenesis as well as during chronic epilepsy. As anesthesia is usually unavoidable for preclinical PET imaging and influences the distribution of the radiotracer, four different protocols were compared.

Procedures

We investigated ¹⁸F-FDG uptake phase in conscious rats followed by a static scan as well as dynamic scans under continuous isoflurane, medetomidine-midazolam-fentanyl (MMF), or propofol anesthesia. Furthermore, we applied different analysis approaches: atlas-based regional analysis, statistical parametric mapping, and kinetic analysis.

Results

At baseline and compared to uptake in conscious rats, isoflurane and propofol anesthesia resulted in decreased cortical ¹⁸F-FDG uptake while MMF anesthesia led to a globally decreased tracer uptake. During epileptogenesis, MMF anesthesia was clearly best distinctive for visualization of prominently increased glucometabolism in epilepsy-related brain areas. Kinetic modeling further increased sensitivity, particularly for continuous isoflurane anesthesia. During chronic epilepsy, hypometabolism affecting more or less the whole brain was detectable with all protocols.

Conclusion

This study reveals evaluation of anesthesia protocols for preclinical ¹⁸F-FDG PET imaging as a critical step in the study design. Together with an appropriate data analysis workflow, the chosen anesthesia protocol may uncover otherwise concealed disease-associated regional glucometabolic changes.

Effects of dexmedetomidine on glucose-related hormones and lactate in non-diabetic patients under general anesthesia: a randomized controlled trial

BACKGROUND

To explore the effects of dexmedetomidine on glucose-related hormones and lactate levels in non-diabetic patients undergoing malignant gastrointestinal tumor radical resection.

METHODS

Groups D1 and D2 received dexmedetomidine loading dose 1 μg/kg and maintenance dose 0.25 and 0.5 μg/kg/h, respectively. Group C received saline solution. Glucose, lactate, insulin, glucagon, cortisol, epinephrine, norepinephrine and dopamine levels were measured before dexmedetomidine infusion (T1), 1 h after surgery beginning (T2), at surgery ending (T3), and 1 h after transfer to the post-anesthesia care unit (T4).

RESULTS

Compared with group C, glucose levels increased in group D2 at T2 and reduced in groups D1 and D2 at T4. Lactate levels reduced in groups D1 and D2 at T4. A positive correlation between glucose and lactate levels was found in all groups. Compared with group C, insulin level reduced in group D2 at T2; glucagon levels reduced in groups D1 and D2 at T4; cortisol levels reduced in group D1 at T4 and in group D2 at T3 and T4; epinephrine and norepinephrine levels reduced in group D1 at T4 and in group D2 at T2 and T4; and dopamine level reduced in group D2 at T4.

CONCLUSIONS

Dexmedetomidine loading dose 1 μg/kg and maintenance dose 0.25 μg/kg/h produces a stable insulin level and significant postoperative decreases in glucagon, cortisol, epinephrine and norepinephrine secretion with stable maintenance of intraoperative and postoperative blood glucose levels and decreased postoperative lactate levels in non-diabetic patients under general anesthesia.

Conscious rat PET imaging with soft immobilization for quantitation of brain functions: comprehensive assessment of anesthesia effects on cerebral blood flow and metabolism

BACKGROUND

Animal brain functions evaluated by in vivo imaging under anesthesia can be affected by anesthetic agents, resulting in incorrect assessment of physiological brain function. We therefore performed dynamic positron emission tomography (PET) imaging of conscious rats using recently reported soft immobilization to validate the efficacy of the immobilization for brain function assessments. We also determined the effects of six anesthetic agents-a mixed anesthetic agent (MMB), ketamine + xylazine (KX), chloral hydrate (Chloral), pentobarbital (PTB), propofol (PF), and isoflurane (IFL)-on brain function by comparison with conscious rats.

RESULTS

The immobilization enabled 45-min dynamic [¹⁸F]FDG-PET acquisition with arterial blood sampling using conscious rats without the use of special techniques or invasive surgery. The spatial resolution and quantitativity of [¹⁸F]FDG-PET were not significantly lower for conscious rats than for anesthetized rats. While MMB, Chloral, PTB, and PF showed ubiquitous reduction in the cerebral metabolic rates of glucose (CMR_glu) in brain regions, KX and IFL showed higher reductions in cerebellum and interbrain, and cerebellum, respectively. Cerebral blood flow (CBF) was reduced by MMB, KX, PTB, and PF; increased by IFL; and unaltered by Chloral. The magnitude of decrease in CMR_glu and CBF for MMB were not larger than for other five anesthetic agents, although blood glucose levels and body temperature can be easily affected by MMB.

CONCLUSION

The six anesthetic agents induced various effects on CMR_glu and CBF. The immobilization technique presented here is a promising tool for noninvasive brain functional imaging using conscious rats to avoid the effects of anesthetic agents.

Rapid Recovery and Short Duration Anesthesia after Low Dose Ketamine and High Dose Dexmedetomidine in Rhesus Macaques (Macaca mulatta)

Anesthesia in rhesus macaques is required for many procedures. Although ketamine is the backbone of most anesthetic protocols, tolerance to the drug can develop, resulting in the need for higher doses to provide sufficient restraint. Combination with other drugs, such as α-agonists, can be ketamine-sparing, providing for sufficient restraint at lower ketamine doses. In addition, because α-agonists are reversible, recovery from anesthesia has the potential to be much shorter. We hypothesized that use of a low dose of ketamine with a high dose of dexmedetomidine, an α2 receptor selective agonist, in male and female rhesus macaques less than 15 y of age would provide adequate anesthesia for short procedures and that recovery would be faster than in macaques given a higher dose of ketamine (10 mg/kg) alone. We found that the combination, in conjunction with atipamezole for reversal, provided smooth induction of anesthesia and significantly shorter recovery time than did ketamine alone, with no significant effects of sex. The combination of low dose ketamine and high dose dexmedetomidine also provided a 30-min window of anesthesia with analgesia sufficient for mild to moderately painful procedures.

Antidiabetic compounds 8a, 8b, 8k, and 9h enhance insulin secretion: activity and mechanism

PURPOSE

This study primarily investigated the effects of hypoglycemic compounds (Imeglimin derivatives) on insulin secretion in type 2 diabetes mellitus (T2DM), and further explored the possible mechanism underlying these effects.

METHODS

Firstly, Metformin was used as the initiating compound to synthesize three sets of derivatives which contained Imeglimin structure core. At the cellular level, we screened compounds with better effect on the activity of insulin receptor tyrosine protein kinase (IFcTPK) after the islet β cells were treated with the compounds of different concentrations. The insulin secretion was assessed using radioimmunoassay and the cytotoxicity to islet β cells was evaluated by means of MTT assay following treatment with the compounds. The Ca²⁺-related mechanism by which these compounds promote insulin secretion was elucidated with whole cell recordings from current-clamp mode.

RESULTS

Totally, 48 synthesized compounds were generated, wherein 10 compounds could increase the activity of IFcTPK in HIT-T15 cells better among these compounds. The modified Imeglimin, especially in the structure of hydrophilic hydroxyl or piperidine rings, could improve the activity of the compound to promote insulin secretion. Furthermore, the compounds 8a, 8b, 8k, and 9h revealed high insulin secretion-promoting activity. These compounds enhanced insulin secretion in islet β cells by repressing the ATP-sensitive K(+) and voltage-gated K+ pathway.

CONCLUSIONS

Our findings indicate that the hypoglycemic compounds 8a, 8b, 8k, and 9h confer better promotive effect on insulin secretion, which provides a reference for the development of drugs with better hypoglycemic activity.

Effects of dexmedetomidine on glucose homeostasis in healthy cats

OBJECTIVES

Alpha(α)2-agonist administration has been documented to increase blood glucose concentrations in many species. The aim of this study was to further describe the effect of dexmedetomidine on glucose and its regulatory hormones in healthy cats.

METHODS

A randomized crossover study using eight healthy cats with a 14 day washout period was used to assess the effect of dexmedetomidine (10 μg/kg IV) and saline on glucose, cortisol, insulin, glucagon and non-esterified fatty acid (NEFA) concentrations at 0, 20, 60, 120 and 180 mins post-administration. Glucose:insulin ratios were calculated for each time point.

RESULTS

Within the dexmedetomidine group, significant differences (P <0.05) were detected: increased median (range) blood glucose concentrations at 60 mins (11.55 mmol/l [5.9-16.6 mmol/l]) and 120 mins (12.0 mmol/l [6.1-13.8 mmol/l]) compared with baseline (6.05 mmol/l [4.8-13.3 mmol/l]); decreased glucagon concentrations at 120 mins (3.8 pmol/l [2.7-8.8 pmol/l]) and 180 mins (4.7 pmol/l [2.1-8.2 pmol/l]) compared with baseline (11.85 pmol/l [8.3-17.2 pmol/l]); decreased NEFA concentrations at 60 mins (0.281 mmol/l [0.041-1.357 mmol/l]) and 120 mins (0.415 mmol/l [0.035-1.356 mmol/l]) compared with baseline (0.937 mmol/l [0.677-1.482 mmol/l]); and significantly larger (P <0.05) glucose:insulin ratios at 60 mins compared with baseline. Insulin and cortisol concentrations were not significantly changed after dexmedetomidine administration.

CONCLUSIONS AND RELEVANCE

Feline practitioners should be aware of the endocrine effects associated with the use of α2-agonists, particularly when interpreting blood glucose concentrations. The transient effects of dexmedetomidine on glucose homeostasis are unlikely to significantly affect clinical practice.

Optimal Dose of Dexmedetomidine for Perioperative Blood Glucose Regulation in Non-Diabetic Patients Undergoing Gastrointestinal Malignant Tumor Resection: A Randomized Double-Blinded Controlled Trial

PURPOSE

To evaluate the optimal dose of dexmedetomidine for perioperative blood glucose regulation in non-diabetic patients with gastrointestinal malignant tumor.

METHODS

One hundred patients were randomly divided into four groups: control group (group C), dexmedetomidine 1 μg/kg + 0.25 mcg/kg/h (group D₁); + 0.5 mcg/kg/h (group D₂); and + 1 mcg/kg/h (group D₃). Blood glucose concentrations were measured before dexmedetomidine infusion (T₁), 1 h after surgery beginning (T₂), at the end of surgery (T₃), and 1 h in PACU (T₄). Duration of surgery, extubation time, anesthetics doses, adverse reactions, postoperative pulmonary infection, total peritoneal drainage 2 days after surgery and hospital stay were recorded.

RESULTS

Compared with T₁, blood glucose concentrations were higher at T₄ in group C and at T_2-4 in groups D₁, D₂, and D₃ (p < 0.01). Compared with group C, blood glucose concentrations were higher at T₂ and T₃ in groups D₂ and D₃ (p < 0.05), but significantly lower at T₄ in groups D₁, D₂, and D₃ (p < 0.01). Propofol and remifentanil consumption in groups D₁, D₂, and D₃ decreased significantly compared with group C (p < 0.01). In group D₃, doses of ephedrine (p < 0.05) and atropine (p < 0.01) were higher, and extubation time was prolonged (p < 0.01) compared with the other groups. The incidence of bradycardia was higher in group D₃ than that in group C (p < 0.05).

CONCLUSIONS

Dexmedetomidine loading dose of 1 mcg/kg followed by maintenance with 0.25 mcg/kg/h can regulate perioperative blood glucose well in non-diabetic patients undergoing gastrointestinal malignant tumor resection and reduce doses of anesthetics without extending extubation time.

Effects of Epinephrine, Detomidine, and Butorphanol on Assessments of Insulin Sensitivity in Mares

Sympathoadrenal stimulation may perturb results of endocrine tests performed on fractious horses. Sedation may be beneficial; however, perturbation of results may preclude useful information. Four experiments were designed to 1) determine the effects of epinephrine on insulin response to glucose (IR2G), 2) assess the effects of detomidine (DET), alone or combined with butorphanol (DET/BUT), on IR2G and glucose response to insulin (GR2I), and 3) assess the effects of BUT alone on IR2G. In Experiment 1, mares were administered saline or epinephrine (5 μg/kg BW) immediately before infusion of glucose (100 mg/kg BW). Glucose stimulated (P < .05) insulin release in controls at 5 minutes that persisted through 30 minutes; insulin was suppressed (P < .05) by epinephrine from 5 to 15 minutes, rising gradually through 30 minutes. Experiments 2 (IR2G) and 3 (GR2I) were conducted as triplicated 3 × 3 Latin squares with the following treatments: saline (SAL), DET, and DET/BUT (all administered at .01 mg/kg BW). Glucose stimulated (P < .05) insulin release that persisted through 30 minutes in SAL mares; DET and DET/BUT severely suppressed (P < .0001) the IR2G. Sedation did not affect resting glucose and had inconsistent effects on the GR2I when mares were treated with 50 mIU/kg BW recombinant human insulin. Butorphanol had no effect on IR2G. In conclusion, adrenergic agonists severely suppress the IR2G and cannot be used for sedation for this test. The use of DET did not alter the GR2I, and therefore may be useful for conducting this test in fractious horses.

Comparison of the anesthetic effect by the injection route of mixed anesthesia (medetomidine, midazolam and butorphanol) and the effect of this anesthetic agent on the respiratory function

Recently, a mixture of medetomidine, midazolam and butorphanol (MMB) has been used as an injectable general anesthetic agent for laboratory animals. The purpose of this study was to establish data to encourage practical usage of MMB, and to clarify the effects of MMB on the respiratory function in rats. To compare the anesthetic efficacy between the injection routes, the anesthetic effects of MMB by subcutaneous (s.c.) or intraperitoneal (i.p.) injection were evaluated in rats. To assess the respiratory function, the blood gas parameters and electrolytes were assessed in serial venous blood samples collected from before s.c. injection of MMB to 270 min after the injection. Recovery from anesthesia and the respiratory changes after atipamezole injection at 30 min after MMB injection was also examined. Subcutaneous injection of MMB was associated with more rapid induction and a longer duration of anesthesia as compared to i.p. injection. The blood gas analysis findings showed MMB had effects on respiratory function, that is, elevations of the partial pressures of carbon dioxide and bicarbonate and reduction of the blood pH. Atipamezole injection resulted in recovery from the MMB-induced anesthetic effect as well as respiratory depression. In conclusion, MMB provides more effective anesthesia administered by s.c. injection compared to i.p. injection and induces respiratory change. These changes were counteracted by atipamezole. Therefore, we recommend MMB administered by s.c. injection for anesthesia, followed by injection of atipamezole after the operative procedure to allow recovery.

Physiological and biochemical variables in captive tigers (Panthera tigris) immobilised with dexmedetomidine and ketamine or dexmedetomidine, midazolam and ketamine

Physiological and biochemical variables in captive tigers (Panthera tigris) immobilised with dexmedetomidine and ketamine or dexmedetomidine, midazolam and ketamine were evaluated. Thirty tigers received either dexmedetomidine (0.025 mg/kg) and ketamine (3 mg/kg) (group DK) or dexmedetomidine (0.0125 mg/kg), midazolam (0.1 mg/kg) and ketamine (3 mg/kg) (group DMK). Heart rate, SPO2 and blood pressure were measured at five-minute intervals. Arterial pH, PO2, PCO2, glucose, K+ and arterial and venous lactate were measured at 15 and 45 minutes after immobilisation. A generalised linear mixed model was used for statistical comparison. There was no difference within or between groups at any time point for any measured variable. Measured PO2 was 73.2±17.5 mm Hg and SPO2 was 88.9±10.8 per cent. Systolic, mean and diastolic blood pressures were 170.5±48.4, 138.9±41.8 and 121.8±37.2 mm Hg, respectively. Venous lactate was higher than arterial lactate within groups at each time point. Seizure-like behaviour was observed in 25 per cent of tigers in group DK but not in group DMK. The addition of midazolam into a protocol for immobilisation of tigers did not result in a difference in any of the measured variables but may have prevented the development of seizure-like behaviour.

Systemic physiology and neuroapoptotic profiles in young and adult rats exposed to surgery: A randomized controlled study comprising four different anaesthetic techniques

BACKGROUND

Experimental evidence indicates that general anaesthetics can induce apoptotic neurodegeneration in the developing brain. The majority of these studies have been performed in the absence of surgery and it currently remains unclear how the presence of surgical stimuli would influence neuroapoptosis as well as systemic homeostasis. Here we explored this possibility by performing dorsal skin flap surgery in young and adult rats under four distinct currently used anaesthesia regimens.

METHODS

Young (21-days) and adult (2 months) male Sprague-Dawley rats were randomized to 150 min exposure to one of four anaesthetics regimens: (i) sevoflurane/dexmedetomidine, (ii) sevoflurane/fentanyl; (iii) propofol/dexmedetomidine, and (iv) propofol/fentanyl. Animals underwent a dorsal skin flap procedure while physiologic, metabolic and biochemical parameters were closely monitored. Neuroapoptotic profiles were evaluated in the cortex, thalamus and hippocampus (CA1 and CA3) at the end of the procedure in each experimental group.

RESULTS

Significant perturbations of systemic homeostasis were found under all anaesthetic regimens. Hyperglycemia and decreased heart rate were particularly relevant in experimental groups receiving dexmedetomidine, while propofol administration was associated with increased systemic lactate levels and metabolic acidosis. A substantial difference in anaesthesia/surgery-induced neuroapoptosis was found between young and adult rats in several brain regions. Combination of sevoflurane and dexmedetomidine resulted in the highest number of caspase-3 positive cells, although the extent of cell death remained relatively low in all experimental groups.

CONCLUSION

Combination of anaesthesia and surgery induces significant perturbations of physiological parameters in both young and adult spontaneously breathing rats undergoing surgery. These observations further enlighten the need for detailed physiological monitoring under these experimental conditions. Although some statistically significant differences in activated caspase-3 profiles were detected between experimental groups, the overall extent of neuronal cell death remained very low under all conditions questioning, thereby, the physiological significance of apoptotic neurodegeneration in the context of anaesthesia and surgery.

Effects of dexmedetomidine on insulin secretion from rat pancreatic β cells

PURPOSE

Dexmedetomidine acts as a selective α2-adrenergic receptor agonist and an imidazoline receptor agonist, both of which are known to affect insulin secretion. Here, we investigated the effects of clinically relevant concentrations of dexmedetomidine on insulin secretion under in vivo conditions. Furthermore, its underlying mechanisms were examined using isolated islets in vitro.

METHODS

For the in vivo oral glucose tolerance test (OGTT), male Sprague-Dawley rats were randomly allocated to one of three groups (n = 7 in each group): two groups infused with dexmedetomidine at a low (group L) or a high (group H) dose, and one control group infused with the same amount of saline (group C). For the in vitro perifusion study, insulin released from isolated islets was measured during stepwise changes in glucose. Dexmedetomidine (0.1-100 µM) was added to the chamber.

RESULTS

During the OGTT test, the insulin levels in group H were significantly lower than those in group C at 30, 60, and 90 min after glucose load. On the other hand, insulin levels in group L were comparable to those of group C at all time points. In the perfusion study, dexmedetomidine inhibited glucose-stimulated insulin secretion in a concentration-dependent manner. When co-treated with yohimbine, an α2-adrenoceptor blocker, dexmedetomidine adversely increased glucose-induced insulin secretion. However, co-treatment with idazoxan, an antagonist for α2-adrenergic and imidazoline receptors, completely abolished the action of dexmedetomidine.

CONCLUSIONS

Dexmedetomidine had no effect on insulin secretion at sedative dose, whereas it significantly inhibited insulin secretion at supraclinical high concentrations mainly via the α2-adrenoceptor.

Molecular targets and mechanism of action of dexmedetomidine in treatment of ischemia/reperfusion injury

Dexmedetomidine (DEX), a highly specific α2-adrenergic agonist, which exhibits anaesthetic-sparing, analgesia and sympatholytic properties. DEX modulates gene expression, channel activation, transmitter release, inflammatory processes and apoptotic and necrotic cell death. It has also been demonstrated to have protective effects in a variety of animal models of ischemia/reperfusion (I/R) injury, including the intestine, myocardial, renal, lung, cerebral and liver. The broad spectrum of biological activities associated with DEX continues to expand, and its diverse effects suggest that it may offer a novel therapeutic approach for the treatment of human diseases with I/R involvement.