ABSTRACT
We examined the effects of clonidine injected unilaterally into the rostral ventrolateral medulla (RVLM) of conscious, unrestrained rats. We also examined whether the local alpha(2)-adrenoceptor mechanism contributed to the action of clonidine injected into the RVLM. Injection of clonidine but not vehicle solution significantly decreased the mean arterial pressure (MAP), heart rate (HR), and renal sympathetic nerve activity (RSNA) in conscious, unrestrained rats as well as in propofol-anesthetized rats. The frequency of natural behavior was significantly lower after clonidine injection than after vehicle injection. The depressor and sympathoinhibitory responses were significantly larger in the propofol-anesthetized rats than in the conscious rats. Coinjection of a selective alpha(2)-adrenoceptor antagonist, 2-methoxyidazoxan, with clonidine into the RVLM significantly attenuated the depressor, bradycardiac, sympathoinhibitory, and sedative effects of clonidine injected alone. In conclusion, clonidine injected into the RVLM decreased MAP, HR, and RSNA and caused sedation in conscious, unrestrained rats. The action of clonidine in the RVLM was at least partly mediated by alpha(2)-adrenoceptor mechanisms.
Subject(s)
Clonidine/pharmacology , Medulla Oblongata/drug effects , Adrenergic beta-Antagonists/pharmacology , Animals , Blood Pressure/drug effects , Clonidine/administration & dosage , Consciousness , Functional Laterality , Glutamic Acid/pharmacology , Heart Rate/drug effects , Hexamethonium/pharmacology , Injections , Kidney/innervation , Male , Medulla Oblongata/physiology , Rats , Rats, Sprague-Dawley , Sympathetic Nervous System/drug effects , Sympathetic Nervous System/physiologyABSTRACT
The physical properties of experimental visible light-activated resins containing dyestuff, which could be quickly discolored by irradiation was, evaluated by analyzing light absorbance characteristics and measuring micro Vickers hardness. The experimental resin, which was prepared by mixing equivalent weights of Bis GMA and triethyleneglycol-dimethacrylate, was colored by one of three organic dye stuffs, and camphorquinone and dimethyl-p-toluidine were added to activate polymerization. In the tested materials, the experimental resins containing Methylene blue and Nile blue A were discolored quickly after the start of irradiation, and this was considered to be useful for dental practice because an overfilled margin could be easily identified. The Vickers hardness number of the base resin decreased slightly by a level of 6% by adding the dyestuff.
