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Aim: to investigate the functional interaction of α2-adrenergic and imidazoline receptors recently identified on the sarcolemma of isolated cardiomyocytes for regulation of the intracellular calcium and the production of the signal molecule of nitric oxide (NO)., Materials and Methods: experiments were performed on isolated left ventricular cardiomyocytes of Wistar rats. Potential-dependent Ca2+-currents were measured from the whole-cell by the patch-clamp method in "perforated-patch" configuration. The intracellular calcium and the production of nitric oxide were estimated from the changes in fluorescence intensity of the Ca2+-specific and NO-sensitive dyes at fluorescent or confocal microscope., Results: It has been shown that α2‑adrenergic and imidazoline receptor agonists inhibit L-type Ca2+-currents by themselves, but their effects do not develop against each other's background. The blockade of key effector molecules: protein kinase B (Akt kinase) for α2‑adrenergic receptors, and protein kinase C for imidazoline receptors causes the action of agonists to become additive. Both the selective α2‑agonist, guanabenz, and the specific agonist of the first type imidazoline receptors, rilmenidine, show an additional inhibition of Ca2+-currents against the basal background already reduced by the activation of one of the two receptor systems. Wherein rilmenidine increases the level of free  Ca2+ in the cytosol, and guanabenz, on the contrary, decreases it. The action of guanabenz does not develop against the background of rilmenidine, although it, in turn, effectively increases the intracellular level of calcium in guanabenz-pretreated cardiac cells. Activation of α2‑adrenergic receptors leads to significant stimulation of the endothelial isoform of NO-synthase, and as a result to an increase in the NO level. Activation of imidazoline receptors itself does not affect NO synthesis but it prevents the production of NO induced by α2‑agonists., Conclusion: obtained data make it possible to formulate a number of useful recommendations for clinical practice, and also to clarify the non-central peripheral effects arising from the activation of α2‑adrenergic or imidazoline systems under conditions of endogenous hyperactivation on of the two systems.

Glaucoma is the main cause of irreversible blindness in the world. The selective α2 adrenergic receptor agonist brimonidine holds an important place among the hypotensive eye drops. The second part of this review focuses on some important effects of brimonidine that characterizes it as a medication with direct neuroprotective multifactorial action, discusses its influence on ocular blood flow and highlights its capability to maintain normal autoregulation of ocular blood flow.

Analgesia of children operated on the lumbosacral segments is discussed. Balanced total anesthesia was used with caudal epidural blocking by a combination of alpha 2-agonist clofelin, local amide anesthetic bupivacaine, and narcotic analgesic promedol. Injection of a combination of clofelin (0.01% solution) in a dose of 1 microgram/kg, standard dose of 0.25% bupivacaine solution with adrenaline (1:200,000) in a dose of 0.3 ml/kg, and promedol in a dose of 0.2 mg/kg into the epidural space via the caudal approach in the presence of superficial anesthesia with halothane (0.2-0.4 vol/%), nitrogen oxide and oxygen in 2:1 ratio ensured adequate analgesia and effective neurovegetative protection both during the operation and the first 25 h after it.

Clonidine in a dose of 2.5 to 3 mg/kg was used as a component of anesthesia in 150 patients aged 60 to 85. Essential hypertension of the second-third stages was diagnosed in 57% patients (group 1), systolic sclerotic arterial hypertension (SSAH) in 43% (group 2). Anesthesia was characterized by stable hemodynamics; however, analysis within the groups showed an increase of systolic and diastolic arterial pressure in 40% patients in group 2. There were no clinical signs of inadequacy of anesthesia. Remembering about the reduction of the reserve potential of the cardiovascular system in this cohort of patients, neurovegetative inhibition was supplemented by peripheral a-adrenoblocker droperidol, starting from the test dose of 1.25 and increasing it to 5 mg over the course of anesthesia; this led to stabilization of the peripheral and improvement of the central hemodynamics. Differences in the changes of central hemodynamics may be explained by specific features of circulation in patients with essential hypertension and SSAH, as well as by a higher tone of the sympathetic component of the CNS in SSAH patients.

Clofelin--2-(2,6-dichlorphenylamino)-2-imidasoline, an analoque of foreign-made clonidine (St155, catapresan, hemiton, etc) was subjected to a pharmacological study. In animals the drug produces first a rise and then protracted fall of the arterial pressure, reduces the frequency of cardiac contractions, lessens reflex hypertension that develops on compression of carotid arteries. When used in low doses it depresses the motor activity in unanesthetized animals and produces symptoms that bear evidence to its adrenomimetic action, e.g. exophthalmos, piloerection. Hypertension provoked by clofelin is caused by its peripheral and hypotension--by the central alpha-adrenomimetic action. The results of the present investigation prove clofelin to be identical with corresponding foreign drugs.