Drugs online research references
J Cardiovasc Pharmacol. 1983 Sep-Oct;5(5):818-21.
Effects of a cardiotonic agent, TA-064, on isolated canine cerebral, coronary, femoral, mesenteric, and renal arteries.
Ozaki N, Bito K, Kinoshita M, Kawakita S.
We investigated the effects of a newly synthesized cardiotonic agent, TA-064, on helical strips of isolated canine cerebral, coronary, femoral, mesenteric, and renal arteries. TA-064 had no effect on isolated arterial strips under resting tension. When the arterial strips were partially contracted with prostaglandin F2 alpha, TA-064 caused markedly significant concentration-related relaxations in coronary arterial strips. However, the maximum relaxation induced by TA-064 in renal, mesenteric, and femoral arterial strips was only one-third or less of the coronary artery. On the other hand, cerebral arterial strips generated negligible responses to TA-064. Relaxation of renal, mesenteric, and femoral arteries was not potentiated by pretreatment with 10(-5) M phenoxybenzamine. The concentration-response curve for TA-064 in coronary artery was shifted to the right to a similar extent by exposure to 2 X 10(-7) M propranolol and 2 X 10(-7) M metoprolol. On the other hand, relaxation of renal arterial strips was only slightly attenuated by metoprolol but was inhibited by propranolol. Droperidol (3 X 10(-5) M) failed to significantly alter the concentration-response curve for TA-064 in coronary artery. These results indicate that TA-064 causes coronary arterial vasodilatation mediated by beta 1-adrenoceptors. It would further appear that the same mechanism may be responsible for the positive inotropic action of TA-064.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6195470&dopt=Abstract
Methods Find Exp Clin Pharmacol. 1995 May;17(4):241-8.
Microwave-induced lethal heat stress: effects of phentolamine, prazosin and metoprolol.
Jauchem JR, Frei MR, Chang KS, Berger RE.
Radiofrequency Radiation Division, Armstrong Laboratory, Brooks Air Force Base, Texas, USA.
Previous studies have shown that adrenergic antagonists can alter physiological responses to microwave-induced heating. In the present experiments, 33 ketamine-anesthetized Sprague-Dawley rats were exposed to 2450-MHz microwaves at an average power density of 60 mW/sq cm (whole-body average specific absorption rate of approximately 14 W/kg) until death occurred. The effects of intraarterial injections of the nonselective alpha-adrenoceptor antagonist phentolamine (10 mg/kg body weight), the alpha 1-adrenoceptor antagonist prazosin (5 mg/kg), and the beta 1-adrenoceptor antagonist metoprolol (2 mg/kg) on physiological responses (including changes in body temperature, heart rate, blood pressure, and respiratory rate) were examined. A group of saline-injected animals was included for comparison. There were no significant differences in lethal temperatures, survival times, or rates of temperature change among the different groups. In all groups, heart rate increased continuously during exposure; mean arterial blood pressure increased until colonic temperature reached 41-41.5 degrees C, and then decreased. These heart rate and blood pressure changes were similar to those that occur during environmental heat stress. Despite differences in absolute values of heart rate and mean arterial blood pressure among groups, there were no significant differences in changes from baseline levels among groups. From these results, taken together with previous findings in our laboratory, it may be hypothesized that selective alpha 1 blockade (without concurrent alpha 2 blockade) and beta 2 blockade (with or without concurrent beta 1 blockade) are effective in altering physiological responses to microwave exposure.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7475510&dopt=Abstract
Arzneimittelforschung. 1984;34(9):1025-30.
[Maternal and fetal hemodynamics under simultaneous beta stimulation and beta1 blockade in a tocolysis model. Considerations on status of the neonatal beta receptor and transplacental passage of metoprolol]
[Article in German]
Siekmann U, Heilmann L, Brodde OE.
This report summarizes the clinical experiences in the treatment of preterm labor using the combination of hexoprenaline and the beta 1-antagonist metoprolol. We found a dose dependency in the antagonism of positive inotropic effects primarily induced by the beta-stimulator hexoprenaline. To verify the pharmacological properties of metoprolol in transplacental passage we evaluated the plasma concentration of metoprolol in umbilical cord blood. There is quite a low concentration of the beta-blocker nearly 24 h after the last course of administration. The beta 2-receptor density--determined by (+/-)-125-iodocyanopindolol (ICYP) binding--and beta 2-receptor responsiveness--assessed by cyclic AMP response to isoprenaline stimulation--in lymphocytes derived from neonatal blood were also investigated. These results were compared with identical investigations in adult lymphocytes. The results indicate that in neonates beta 2-receptor density and responsiveness is significantly diminished in comparison to the adult controls. The present investigations induce a new concept for the estimation of concomitant fetal cardiovascular reactions under maternal beta-blockade.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6150714&dopt=Abstract
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