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Biomedical subjects

J Antunes-Rodrigues

Publications and source records attributed to J Antunes-Rodrigues.

151 records · Page 9Linked to original sources
PubMedDate not supplied

Natriuresis, kaliuresis and diuresis in the rat following microinjections of carbachol into the septal area.

The effects of intraseptal injection of carbachol on natriuresis, kaliuresis and diuresis has been studied in conscious, unrestrained water-loaded male rats. Urinary sodium and potassium excretion increased following injections into the septal area. The intensity of the natriuresis and kaliuresis was dose-related. An antidiuretic effect was also observed. The Na+/K/ ratio increased with increasing doses of carbachol, indicating that the rise in urinary sodium exceeded that of potassium. Systematic mapping of the septal area yielded about the same results for all sites, excepting a zone located in the anterior-dorsal part of the medial nucleus which appeared more sensitive. The natriuretic effect of intraseptal carbachol in adrenalectomized rats demonstrated the secondary role played by the adrenals. Contrariwise the decrease of the natriuretic effect observed either in hypophysectomized rats or in rats bearing a median eminence lesion receiving intraseptal carbachol showed the important participation of these structures in urinary Na+ excretion. Adrenalectomy or median eminence lesions did not modify the kaliuretic response while hypophysectomy produced a transitory diminution. This fact favours the hypothesis of different mechanisms involved in Na+ and K+ excretion following intraseptal carbachol. These results leave open the question as to mechanism of action but suggest a possible role of the pituitary in mediating the responses. Also, the possibility of a role played by hemodynamic shifts is suggested.

Adrenal Glands↗
PubMedDate not supplied

Effect of gonadal steroids on hypothalamus and anterior pituitary endo-oligopeptidase B (proline-endopeptidase) activity in castrated female rats.

In the present study we investigated the possible participation of endo-oligopeptidase B (poline-endopeptidase) in the control of gonadotrophin secretion through the control of LH-RH inactivation. This enzyme selectively hydrolyzes the Pro9-Gly10-NH2 peptide bond of LH-RH, thereby inactivating this substance. The enzyme activity was evaluated using a specific colorimetric substrate, i.e., Z-Gly-Pro-SM. Female adult Wistar rats were submitted to castration, experimental situations that are known to produce changes in gonadotrophin secretion. Hypothalamic and pituitary endo-oligopeptidase B activity was shown to be present predominantly in the soluble fraction of the enzyme preparations. The results also indicated that endo-oligopeptidase B activity adult female rat pituitary decreased after castration and increased after administration of estradiol and progesterone to castrated animals. The present results lead us to suggest that anterior pituitary endo-oligopeptidase B may be related to the control gonadotrophin secretion in female rats.

Animals↗
PubMedDate not supplied

Hypothalamic action of atrial natriuretic factor to inhibit vasopressin secretion.

The ability of synthetic atrial natriuretic factor (ANF) to inhibit vasopressin (AVP) release, as well as its action to inhibit water intake and salt preference in the rat, suggest a role for the peptide in the hypothalamic control of fluid volume in addition to its established actions in the kidney. We report here evidence for a direct, hypothalamic site of action of ANF to inhibit, specifically, AVP secretion. Third cerebroventricular infusion of 1.0 (p less than 0.05) and 2.0 (p less than 0.025) nmoles ANF significantly inhibited AVP release in euvolemic, normally hydrated rats while IV doses of ANF failed to significantly alter AVP release except when 5 nmoles (p less than 0.05) were infused. No significant effects on oxytocin (OT) release were observed. Vasopressin release from median eminence or pituitary, neural lobe explants during static, in vitro incubations was not significantly altered by doses of ANF ranging from 10(-12) to 10(-7) molar. Release of AVP during perifusion of neural lobe explants in the presence of ANF was similarly unaffected. However, AVP and not OT release from hypothalamo-neurohypophysial system explants was significantly inhibited in the presence of 10(-8) and 10(-7) M ANF, suggesting an action of the peptide at the levels of the AVP-producing cell bodies in the included supraoptic nucleus either directly or via an action on an interneuron, and not at the AVP-containing terminal fields in the median eminence or neural lobe.

Animals↗
PubMedDate not supplied

Effects of intrathecal sufentanil on plasma oxytocin and cortisol concentrations in women during the first stage of labor.

BACKGROUND AND OBJECTIVES: Intrathecal sufentanil provides analgesia comparable to epidural bupivacaine for the first stage of labor. Both epidural local anesthetics and intrathecal opioid reduce some parameters of the neuroendocrine response to labor pain and the reflex release of oxytocin in animals. In humans, epidural local anesthetics only reduce the spurt release of oxytocin. This study compared the effect of intrathecal sufentanil and epidural bupivacaine administration on the plasma concentration of oxytocin and cortisol in women with labor pain during the first stage of labor. METHODS: Thirty healthy parturients requesting analgesia were enrolled in this randomized and open-label study. Each patient was in spontaneous labor at greater than 5 cm cervical dilatation. Using a combined spinal and epidural technique, patients received either intrathecal sufentanil 10 microg (SUF = intrathecal sufentanil group) or epidural plain bupivacaine 0.25%, 12 mL (BUPIV = epidural bupivacaine group). Analgesia was assessed using a visual analog scale, and blood samples for oxytocin and cortisol plasma concentration measurements were collected immediately before analgesia and 15, 30, 60, and 90 minutes after induction of the analgesia. Plasma cortisol and oxytocin concentrations were determined by specific radioimmunoassay. The values were expressed as mean +/- SEM. RESULTS: Intrathecal sufentanil provided faster and more complete analgesia within 15 and 30 minutes of its administration, compared with epidural bupivacaine. Plasma oxytocin concentrations were similar in the 2 groups before analgesia (7.24 +/- 2.1 and 6.6 +/- 3.1 pg/mL SUF and BUPIV, respectively). It decreased significantly in the SUF and increased in the BUPIV after analgesic administration. Cortisol concentrations were elevated in both groups before analgesia (51.6 +/- 5.3 and 54.2 +/- 4.8 microg/dL SUF and BUPIV, respectively). Both analgesic treatments significantly decreased the plasma cortisol levels. CONCLUSIONS: Intrathecal sufentanil analgesia decreases plasma concentrations of oxytocin and cortisol in women with labor pain during the first stage of labor, but epidural bupivacaine only reduced the cortisol concentration.

Adult↗