Biomedical subjects

A Costuleanu

Publications and source records attributed to A Costuleanu.

6 recordsLinked to original sources

PubMed1997

Vasorelaxant properties of brefeldin A in rat aorta.

The effects of brefeldin A, a putative specific agent that disassembles the Golgi apparatus were assessed on the contractility of de-endothelised rat aorta. Brefeldin A inhibited, either as pre- or as post-treatment, the contractions elicited by K+ (75 mM) or phenylephrine (10 microM), being significantly more potent upon the latter. The thapsigargin (1 microM)-induced rat aorta contraction was less sensitive to brefeldin A inhibition. Pre-treatment with brefeldin A (30-100 microM) did not affect phenylephrine-induced transient contractions in Ca2+-free medium, but strongly inhibited the phenylephrine-induced sustained contractions upon re-admission of Ca2+ to the medium. Brefeldin A was unable to prevent Ca2+ stores refilling. We concluded that brefeldin A inhibits Ca2+ entry but not the pathways activated after Ca2+ stores depletion or the pathways responsible for replenishment of these stores in rat aorta, presumably by disassembling the Golgi apparatus network.

Adrenergic alpha-Agonists↗

PubMedDate not supplied

TLC characterization of small unilamellar liposomes containing D-myo-inositol derivatives.

The thin-layer chromatographic (TLC) behaviour of small unilamellar liposomes containing inositol phosphates (IPs) was studied. The vesicles contained different concentrations of D-myo-inositol 1,4,5-triphosphate (IP3), D-myo-inositol 1,2,6-triphosphate (alpha-trinositol, PP 56, a novel Perstorp Pharma derivative), D-myo-inositol 1,3,4,5-tetraphosphate (IP4), D-myo-inositol 1,3,4,5,6-pentakisphosphate (IP5) and D-myo-inositol 1,2,3,4,5,6-hexakisphosphate (IP6). Migration of all liposome batches was compared to that of control liposomes (multilamellar and small unilamellar, both containing only triple-distilled water), and to that of free phosphatidylcholine (PC). The same amount of lipid was used in all situations. Thin-layer chromatography was performed with silica gel as adsorbent. The developing solvent was an n-buthanol:ethanol:water mixture in a 4:3:3 volume ratio. At doses higher than 10(-2) M liposomes containing alpha-trinositol and IP6 had a different migration than PC, MLV or SUV as well as all batches of liposomes. Physiological studies (using as model endothelized rat aorta rings) proved that in this situation they had no effects.

Animals↗

PubMedDate not supplied

TLC characterization of liposomes containing angiotensinogen, angiotensine I, angiotensine II and saralazin.

Recent studies have described intracellular binding sites for angiotensine II. In vascular smooth muscle it was found that intracellular injection of angiotensin II increases the Ca2+ level. An alternative method for intracellular delivery of drugs is represented by using liposomes. Thus, the aim of this study was to characterize liposomes filled with angiotensinogen, angiotensine I (Ang I), angiotensine II (Ang II), and saralasin by a TLC method and examine the physiological effects of these on rat vascular smooth muscle. Ang II (for all concentrations tested in the aqueous phase) and Ang I (for concentrations less than 10(-4)M) did not affect the thin-layer chromatography migration of this type of vesicle, suggesting that dose-dependent effects on physio-pharmacological experiments could be studied. On the other hand, this type of experiment could not be performed for salarasin- or angiotensinogen-filled liposomes. Administration of liposomes containing Ang II (10(-6)M), Ang I (10(-6)M), angiotensinogen (10(-6)M) and saralasine (10(-6)M) caused the contraction to isolated rat aorta smooth muscle, suggesting the presence of active intracellular binding sites.

Angiotensin I↗

PubMedDate not supplied

[The physio-pharmacological and pathological implications of the endothelins].

The papers of Furchgott and Zawadzki have widely enlarged the research field concerning the dependence of the vascular smooth muscle reactivity upon the endothelium. Besides the relaxing factors produced by the endothelium, vasoconstrictor factors have been also emphasized. The endothelial cells are also able to synthesize endothelin-like vasoconstrictor peptides. There were described some types of endothelins. They all have common structural features but substitution of certain amino-acids leads to specific effects, and all of them keep the vasoconstrictor properties. The endothelins are normal constituents of a lot of tissues (brain, endothelial and tumor cells, the spinal nodes) and of the body fluids (plasma, urine, cerebrospinal fluid etc.). The endothelins accomplish their effects by the specific receptors located in the muscle and endothelial cell membrane (ET-A and, respectively, ET-B). The endothelins action in the cell is basically based on the cytosolic Ca2+ raise. The endothelins have numerous pathological implications, especially concerning the cardiovascular pathology.

Animals↗

PubMedDate not supplied

[Dipsogenic behavior].

Hydroelectrolytic homeostasis assumes balance between the intake and elimination of water and electrolyte, according to the necessities of the organism. The water intake is made mainly by fluid ingestion. The necessity to drink is a subjective sensation which is the expression of an objective situation, because it translates the homeostatic deviations. The ingestion of water is motivated (reparatory thirst), when it appears after hydric and electrolytic imbalances (ex. a decrease of the fluid volume, increase in the plasmatic osmolarity) or is manifested without an objective reason (unreparatory thirst).

Animals↗

PubMedDate not supplied

[The effects of the intraventricular administration of captopril on water and ion metabolism in the rst].

The effects of the conversion enzyme on the hydroelectrolytic balance in adult rats, maintained in standard lab conditions have been followed. The administration protocol for the conversion inhibitor (captopril) produced a blocking of the transformation of angiotensin I in angiotensin II only at the level of the cerebral structures, during the whole period of the treatment (40 micrograms/kg x 3/24 hours). Following the intracerebroventricular (ICV) administration of captopril, the fluid ingestion decreased diuresis and urinary elimination of Na+ and Ca++ increased. The results plead for the existence of a cerebral renin-angiotensin system, which intervenes in the control of the hydroelectrolyte metabolism.

Angiotensin-Converting Enzyme Inhibitors↗