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Biomedical subjects

R Vergona

Publications and source records attributed to R Vergona.

22 records · Page 2Linked to original sources
PubMed1982

The cardiovascular and autonomic properties of N-phenylpiperazine (NPP) in several animal models.

A number of isolated tissue and intact animal models were utilized to investigate in more detail the cardiovascular actions of N-phenylpiperazine (NPP), a known compound having adrenergic blocking properties. In isolated tissues its autonomic profile is characterized by alpha and beta adrenergic blocking activity. Compared to other beta receptor antagonists, NPP displays moderate in vitro beta-1 blockade in guinea-pig atria. Cumulative administration of NPP (0.1--0.3 mg/kg i.v.) in the intact dog also produces dose-dependent inhibition of myocardial contractility following isoproterenol administration. The oral antihypertensive potency of NPP in the deoxycorticosterone acetate hypertensive rat is compared with phenoxybenzamine and labetalol. Its profile is similar to labetalol but differs from phenoxybenzamine, causing a fall in blood pressure and a decrease in heart rate. Hemodynamic data obtained with NPP in the anesthetized animal reveal a complex cardiovascular profile involving the interactions of the sympathetic nervous system. Canine hind limb perfusion studies using cumulative doses (0.1--0.3 mg/kg i.v.) appear to preclude a direct vasodilator mechanism in the reserpinized-pretreated animal. In other studies, nonselective vasoconstrictor responses induced by exogenous administration of norepinephrine and lumbar sympathetic nerve stimulation are inhibited to the same degree by NPP (0.1--10 mg/kg i.v.) autonomic interactions with NPP in the nictitating membrane provide evidence for inhibition of neuronal catecholamine uptake and catecholamine release. From the data obtained in the present study, it is suggested that NPP has a predominant influence on the response of the sympathetic nervous system to provide a unique cardiovascular profile. The manner in which blood pressure is regulated by either direct or nonselective mechanisms will be discussed.

Adrenergic alpha-Antagonists↗
PubMed1976

A comparative diuretic and tissue distribution study of bumetanide and furosemide in the dog.

Intravenous dose-response data obtained from renal clearance studies in anesthetized dogs indicated that bumetanide was approximately 30-fold more potent than furosemide in enhancing sodium excretion. After the administration of 0.01 mg/kg of bumetanide or 1.0 mg/kg of furosemide, the relationship between i.v. diuretic activity and tissue distribution was evaluated. In dog renal clearance experiments, bumetanide and furosemide significantly enhanced urine flow, sodium and potassium excretion. Inulin clearance as an estimate of glomerular filtration rate was not altered by either drug, but sodium reabsorption was decreased with bumetanide (13%) and furosemide (12%). At these diuretic doses, both compounds were bound to dog plasma protein to about the same extent (86-91%), although total plasma levels were 100-fold higher for furosemide. Within 1/2 hour after the i.v. administration of 14C-bumetanide or 14C-furosemide, 86 to 99% of the 14C in urine, plasma, kidney, and liver appeared as unchanged drug. One minute after maximal diuresis bumetanide was found to have a higher affinity (3-fold) for kidney compared to furosemide. These data offer a possible explanation for the i.v. diuretic potency difference between these two compounds. Furthermore, the lack of significant difference in plasma protein binding and the absence of urinary metabolites of either drug suggest that other factors may also contribute to the marked differences in diuretic activity between bumetanide and furosemide.

Animals↗
PubMed1975

Fluorescamine as a terminating agent in solid phase peptide synthesis.

Fluorescamine was shown to be an excellent terminating agent for blocking unreacted amino groups during solid phase peptide synthesis. A comparison of the termination efficiency of fluorescamine versus that of acetylation revealed that the former method gave superior products as assessed by peptide analysis, dansyl-amino end group determination and biological assay. In addition, fluorescamine terminated fragments were converted to non-fluorescent spirolactones during the deprotection stage. These spirolactones were stable to subsequent solid phase reaction conditions and were readily removed from the target peptide.

Acetylation↗