Biomedical subjects
Publications and source records attributed to D Glock.
Twenty Sprague Dawley rats, aged 22 to 26 months were given subcutaneous injections of 4.5 mg/kg methylphenidate or distilled water. Twelve minutes after the single injection was given, rats began 90 trials of avoidance conditioning. Drug animals made significantly more correct responses than did the control animals. tresults indicate that use of methylphenidate in aged rats improved avoidance learning.
Contrast ultrasonography may be used to assess regional tissue perfusion. The purpose of this study was to evaluate the safety and efficacy of a new, commercially prepared ultrasound contrast agent (Albunex) in dogs. The injections were administered from peripheral intravenous (IV), right atrial (RA), and pulmonary artery (PA) sites. Acute pulmonary hemodynamic and gas exchange effects of low-dose (0.5, 1.0, 2.0 ml) Phase I injections, and high-dose (2.0, 5.0, 10, 20 ml) Phase II injections of Albunex were evaluated in nine dogs. Immediately before and after each injection, pulmonary artery pressure (PAP) and oxygen tension (PO2) were determined. In addition, left ventricular cavity opacification was assessed visually and by videodensitometric off-line analysis. Visual assessment was performed by four blinded observers who graded on a scale of 0 to 3 (0 = no contrast enhancement of the left ventricular (LV) cavity; 1 = weak or suboptimal contrast enhancement; 2 = optimal or excellent contrast enhancement; and 3 = attenuation of the ultrasound signal following a contrast injection). Peak pixel intensity was also determined with videodensitometric analysis. Results showed that significant changes in PAP or PO2 were not noted after Albunex injections, regardless of injection site or dose range. The average change in PAP after Albunex injection was 1.0 mm Hg +/- 1.2 mm Hg (NS), and the average change in PO2 after Albunex injections was 6.2 mm Hg +/- 6.7 mm Hg (NS). The left ventricular cavity peak pixel intensity was dependent on both injection site (PA = RA > IV) and dose range (2.0 = 1.0 > 0.5).(ABSTRACT TRUNCATED AT 250 WORDS)
Intravenous (i.v.) infusions of SCH 23390 (R-(+)-8-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine-7- ol) produced dose-related antagonism of dopamine (DA)-induced renal vasodilation in phenoxybenzamine-treated dogs at infusion rates of 0.05, 0.15, and 0.5 microgram/kg/min. The highest rate of infusion, 0.5 microgram/kg/min, resulted in pronounced antagonism of this DA1-receptor-mediated response. In contrast, a 10 times higher infusion rate, 5 micrograms/kg/min, did not antagonize the following DA2-mediated responses: increase in femoral blood flow produced by apomorphine and piribedil in untreated dogs; and N,N-di-n-propyl DA (DPDA)-induced inhibition of the tachycardia produced by cardiac accelerator nerve stimulation. Infusions of 0.5 micrograms/kg/min or greater of SCH 23390 did not affect the actions of agonists of alpha1-, alpha2-, beta1-, and beta2-adrenergic, histamine, serotonin, and cholinergic receptors, or the vasodilation produced by bradykinin. At the infusion rates used in these studies, SCH 23390 did not affect arterial blood pressure or heart rate. These data indicate that SCH 23390 is the most specific and selective antagonist of DA1 receptors thus far described. Accordingly, SCH 23390 should be extremely useful in investigations of potential physiological and pathological roles of DA and in the classification of DA receptors.