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M Anwar

Publications and source records attributed to M Anwar.

At least 37 records · Page 2Linked to original sources
PubMed1996

Blood pressure ranges in premature infants: II. The first week of life.

OBJECTIVE: To examine the arterial blood pressure in the first week of life in a healthy premature population. DESIGN: Population-based cohort study. SETTING: Three intensive care nurseries in central New Jersey. PATIENTS: Premature infants with birth weights less than 2000 g. MAIN OUTCOME MEASURES: We documented daily maximum and minimum systolic and maximum and minimun diastolic blood pressures during the first 7 days of life. To examine the effects on the ranges of blood pressure, we identified four groups of infants: (1) healthy infants without any of the major risk factors (n = 193); (2) infants who were mechanically ventilated but free of any of the other conditions (n = 225); (3) infants with histories of maternal hypertension or preeclampsia (n = 38) and (4) infants with low Apgar scores (less than 3 at 1 minute and less than 6 at 5 minutes) regardless of the presence of other conditions (n = 86). RESULTS: Blood pressure increased steadily in the first week of life in all four groups. There was no relationship between any of the four blood pressure variables, or trends in blood pressure over time, with birth weight, gender, or race. Regression equations (based on all infants with available data) for blood pressure ranges by day of life revealed that the maximum systolic blood pressure increased by 2.6 mm Hg/d, the minimum systolic blood pressure increased by 1.8 mm Hg/d,the maximum diastolic blood pressure increased by 2.0 mm HHg/d, and the minimum diastolic blood pressure increased by 1.3 Hg/d. CONCLUSIONS: Infants with birth asphyxia and ventilated infants had significantly lower systolic and diastolic blood pressures than healthy infants.

Age Factors↗
PubMed1996

Effects of hemorrhagic hypotension on cerebral blood flow and perfused capillaries in newborn pigs.

We examined the effect of hemorrhagic hypotension on cerebral blood flow and perfused capillaries in newborn pigs, 2-10 days old. Cerebral blood flow was measured by using radioactive microspheres, perfused capillaries were determined by infusing a plasma marker, fluorescein isothiocyanate (FITC) - dextran (molecular mass 147,000 Da), and total capillaries were determined by staining with alkaline phosphatase. Rapid removal of 66 +/- 16 mL of blood resulted in a fall in mean blood pressure from 68 +/- 6 to 31 +/- 4 mmHg (1 mmHg = 133.3 Pa), an increase in heart rate from 137 +/- 18 to 240 +/- 34 beats/min, and a drop in arterial pH from 7.33 +/- 0.05 to 7.23 +/- 0.07. PCO2 was controlled by mechanical ventilation (36 +/- 4 mmHg before hemorrhage and 35 +/- 5 mmHg after hemorrhage) and PO2 remained stable (89 +/- 11 mmHg before hemorrhage and 94 +/- 10 mmHg after hemorrhage). Blood flow (n = 9) did not fall significantly in any brain region after hemorrhage. The percentage of perfused capillaries/mm2 (control, n = 7, hemorrhage, n = 6) was reduced in all brain regions during hypotension (cortex from 72 +/- 8 to 57 +/- 8%, cerebellum from 75 +/- 10 to 52 +/- 10%, and medulla from 76 +/- 8 to 51 +/- 9%). Similar results were seen for perfused capillary surface area We conclude that hemorrhagic hypotension resulted in a variable blood flow response with no significant reduction in cerebral blood flow but a reduction in perfused capillary number and surface area in all brain regions studied. We speculate that decreased capillary perfusion may be a contributing factor in diffuse neuronal injury after severe hemorrhagic hypotension.

Animals↗
PubMed1995

Sex allocation and population structure in malaria and related parasitic protozoa.

Here we demonstrate how sex allocation theory, one of the best verified areas of metazoan evolutionary biology, can be successfully applied to microparasitic organisms, by relating parasite prevalence and sex ratio in the Haemosporina. Members of this taxon, which includes Plasmodium, are parasitic protozoa with obligate sexual cycles in which dioecious haploid gametes drawn from the peripheral blood of a vertebrate host fuse within a dipteran vector. Consequently mating takes place within a highly subdivided population, a condition known to promote local mate competition and inbreeding and hence the evolution of female-biased sex ratios. We used an epidemiological framework to investigate mating patterns and sex ratio evolution within natural populations of these parasites. This phenotypic approach compliments more conventional biochemical approaches to the population genetics of parasitic protozoa. Data are presented which support a theoretical relation between transmission-stage sex ratio and prevalence across parasite populations. These results are consistent with a large inter-population variation in genetic structure and argue against sweeping generalizations about the clonality or otherwise of populations of these parasitic protozoa.

Animals↗
PubMed1995

Medullary visceral reflex circuits: local afferents to nucleus tractus solitarii synthesize catecholamines and project to thoracic spinal cord.

Visceral feedback circuits in lower brainstem were elucidated with retrograde tracers by mapping neurons that issue local projections to the general visceral afferent division of the nucleus tractus solitarii (NTS) and dorsomotor vagal nucleus (DMX) in adult male rats. In study 1, spinal and intramedullary afferents to the visceral-sensorimotor complex (NTS-X) were traced to contiguous populations of cell bodies arranged in cylindrical segmental organization. NTS-X afferents derive from curvilinear arrays of neurons that parallel the efferent radiations of the solitariotegmental tract. Newly discovered afferents arise from circumscribed cell groups in the dorsal reticular formation and periventricular zone. Another source was traced to a paraambigual cell column in the apex of the rostral ventrolateral reticular nucleus (n.RVL). In study 2, catecholaminergic afferents were initially defined with combined retrograde transport-immunocytochemical methods. Deposits of retrograde tracers into NTS-X transported to neurons containing tyrosine hydroxylase (TH) in the A1, C1, and C3 areas or phenylethanolamine N-methyltransferase (PNMT) in the C1 area of the n.RVL and C3 area. In study 3, it was revealed that NTS-X afferents arise, in part, as collaterals of thoracic reticulospinal neurons. Deposits of the retrograde fluorescent tracer Fluorogold into the upper thoracic cord and rhodamine-labeled microbeads into NTS-X transported to the same neurons within a subambigual locus in n.RVL and parts of nucleus raphe magnus. In study 4, dual retrograde tracer-immunocytochemical analysis demonstrated that catecholamines are synthesized by a subset of neurons in the n.RVL that issue collaterals to the NTS-X and thoracic cord. Double retrogradely labeled TH- or PNMT-immunoreactive cell bodies were restricted to the C1 area within a 450-microns column bordered rostrally by the facial nucleus and ventrally by the medullary subpial surface. We conclude that visceral reflex arcs are reciprocally organized. Targets of NTS projection are also sources of local NTS-X afferent innervation. Catecholaminergic and other local afferents from reticular formation, periventricular, and spinal gray may, via collaterals, simultaneously modulate visceral reflex excitability at the level of NTS and the outflow of autonomic and respiratory motoneurons.

Animals↗
PubMed1995

Disseminated intravascular coagulation in acute leukaemias at first diagnosis.

Haemorrhagic diathesis is the commonest cause of morbidity and mortality in acute leukaemias (AL). It is most commonly due to thrombocytopenia resulting from bone marrow failure. However, in a significant number of cases, disseminated intravascular coagulation (DIC) plays an important part. Previously it was thought that this mechanism was mainly confined to acute promyelocytic leukaemia (APL), but recently it has also been reported to occur in other subtypes of acute leukaemia. We report the results of a study carried out to find the incidence of DIC in various types of AL at the time of first diagnosis and in the absence of other recognisable causes. DIC was observed in 14(13.4%) cases out of 104 cases of AL studied. Nine out of 49(18.4%) cases of AML and 5 out of 55(9.1%) cases of acute lymphoblastic leukaemia (ALL) showed coagulation abnormalities consistent with DIC. Out of the 9 cases of AML showing DIC, 63 (66.67%) belonged to APL (FAB ME) subtype. Three (60%) out of 5 cases of ALL with DIC had T-cell immunophenotype. The results indicate that DIC may also occur in types of AL other than APL, particularly in T-ALL, and should be looked for.

Adolescent↗
PubMed1995

Serum ferritin levels in carriers of beta-thalassaemia trait.

Hypochromic and microcytic red cell morphology is the most commonly encountered abnormality in a clinical laboratory. Most of such cases have iron deficiency anaemia. However, in Pakistan about 5% of the individuals with a hypochromic and microcytic blood picture have the beta-thalassaemia trait. These individuals are more than often in a positive iron balance. However iron deficiency (being common) may be associated with the beta-thalassaemia trait. This study of serum ferritin levels was carried out on 135 confirmed cases of the beta-thalassaemia trait. A ferritin assay was done by a radioimmunoassay technique. The results show that the level of serum ferritin in 100 (74%) cases was within normal limits, in 17 (12.6%) cases it was above the normal range, whereas in 18 (13.4%) cases the level was lower than normal. The importance of serum ferritin estimation in carriers of the beta-thalassaemia trait is highlighted.

Adolescent↗
PubMed1995

Evaluation of M/H ratio for screening of beta thalassaemia trait.

This study was done to evaluate the efficiency of M/H ratio between the percentages of microcytic and hypochromic cells as a screening procedure for thalassaemia trait in Pakistani population. A total of 150 subjects, were included in this study. The analysis of results revealed that M/H ratio is a very sensitive index for beta thalassaemia trait. The sensitivity, predictive value and diagnostic accuracy of the M/H ratio for beta thalassaemia trait was 100%, 90.4% and 90.4% respectively. It also picked up all cases of beta thalassaemia trait with co-existent iron deficiency. It is therefore concluded that M/H ratio is an easy, reliable and sensitive index which can be used for mass screening of beta thalassaemia trait, particularly in a population where iron deficiency is also prevalent.

Adolescent↗
PubMed1995

Granulocytic sarcoma in patients with chronic myeloid leukaemia.

Granulocytic sarcoma is an unusual variant of myeloid malignancy most commonly encountered in the course of chronic or acute myeloid leukaemia. Of 60 patients of chronic myeloid leukaemia studied over 21 months, we encountered 6 (10%) cases of granulocytic sarcoma. Four of these had granulocytic sarcoma on their first presentation. All those who were receiving hydroxyurea did not fare well but one who was put on DAT (daunorubicin, cyftosine arabinocide, 6 thioguanine)regimen went into remission with complete disappearance of lesions.

Adolescent↗
PubMed1994

Adrenergic and non-adrenergic spinal projections of a cardiovascular-active pressor area of medulla oblongata: quantitative topographic analysis.

A cardiovascular-active pressor area of medullary reticular formation was defined by mapping changes in arterial blood pressure produced by microinjections of the neuroexcitatory amino acid, L-Glutamate (L-Glu). Sites where L-Glu provoked pressor responses larger than 10 mmHg were localized to a rostral longitudinal cell column of the nucleus reticularis rostroventrolateralis (n.RVL) extending 450 microns posteriorly to the facial nucleus. Spinal projections from the ventrolateral medulla were studied with a dual retrograde transport-immunocytochemical method. A striking correspondence was observed between the ventrolateral pressor area (VLPA) of n.RVL and rostrocaudal distribution of a circumscribed population of thoracic reticulospinal neurons containing tyrosine hydroxylase (TH)- or phenylethanolamine N-methyltransferase (PNMT)_immunoreactivity. Quantitative analysis revealed that 72% of the total number of retrogradely labeled neurons within the active area were immunocytochemically positive for TH; 28% of the reticulospinal projection cells were immunonegative. Deposits of L-Glu and dye through the same micropipettes verified a consistent correlation of vasopressor sites and the rostral subset of catecholaminergic neurons. Since comparable numbers of cell bodies in the VLPA contain TH and PNMT all are presumed to be adrenergic. At levels of n.RVL immediately adjacent to the VLPA commencing at a level 450 microns caudal to the facial nucleus, sites were unresponsive to Glu-stimulation or vasodepressor. At these levels, only non-adrenergic reticulospinal neurons project to cervical or thoracic spinal segments. We conclude that the VLPA is highly restricted to a narrow column of n.RVL < 0.5 mm in length and corresponds precisely with a population of predominantly adrenergic thoracic reticulospinal neurons that project exclusively to sympathoadrenal preganglionic motoneurons [cf 46]. These findings corroborate the idea that an adrenergic-spinal pathway may play a role in controlling sympathetic outflow.

Animals↗
PubMed1994

Blood pressure ranges in premature infants. I. The first hours of life.

We studied blood pressure in the first hours of life in a cohort of 1105 preterm infants weighing 501 to 2000 gm; these infants represented 83% of all births at these weights that resulted in admission to three intensive care nurseries during a 34-month period between 1984 and 1987. To assess the effects of specific risk factors, we identified 244 healthy infants, 164 infants who received mechanical ventilation but had no other conditions, 47 infants whose only risk factor was the presence of hypertension or preeclampsia in the mother, and 86 infants with depressed Apgar scores regardless of the presence of the other conditions. We documented each infant's minimum and maximum systolic (Smin, Smax) and diastolic (Dmin, Dmax) pressures during the first 3 to 6 hours of life. In the healthy group, Smin was 47 mmHg; Smax, 59 mmHg; Dmin, 24 mmHg; and Dmax, 35 mmHg. In the ventilation group, Smin was 41 mmHg; Smax, 57 mmHg; Dmin, 22 mmHg; and Dmax, 35 mmHg. The Smin and Dmin values were both significantly lower in infants who received mechanical ventilation than in healthy infants (p < 0.01). In the maternal hypertension group, Smin was 49 mmHg; Smax, 59 mmHg; Dmin, 25 mmHg; and Dmax, 34 mmHg. Only the Smin value was significantly higher than in healthy infants. In the group with low Apgar scores, Smin was 33 mmHg; Smax, 51 mmHg; Dmin, 19 Hg; and Dmax, 34 mmHg. Thus all these values were significantly lower than in all the other groups (p < 0.05). Of infants with low Apgar scores, 20% to 50% had values below the 5th percentile for healthy infants. Birth weight and gestational age correlated with blood pressure limits only in the infants with low Apgar scores. We conclude that in healthy premature infants the limits of systolic and diastolic blood pressure are independent of birth weight and gestational age. Infants with low Apgar scores tend to have lower pressures, and infants whose mothers have hypertension have higher pressures than infants in the healthy cohort.

Apgar Score↗
PubMed1994

Comparative assessment of the effects of subdermal levonorgestrel implant system and long acting progestogen injection method on lipid metabolism.

In order to compare the effects of two type of long-acting progestogen contraceptive methods with subdermal levonorgestrel (LNG) implants and depot-medroxyprogesterone acetate (DMPA) injections on lipid metabolism, a clinical cohort study was performed by requiring 25 women in each group adopting either LNG implant or DMPA injection method voluntarily. After 6 months of use, serum levels of triglycerides, total cholesterol, HDL-cholesterol and LDL-cholesterol were determined and compared between the two groups of acceptors. The mean of total cholesterol in LNG implant acceptors was significantly lower than that in DMPA injection acceptors. The mean values of HDL-cholesterol in LNG implant acceptors (41.7 +/- 7.7 mg/dl) and in DMPA injection acceptors (45.0 +/- 9.0 mg/dl) were in the normal range without significant difference between the two groups. The mean value of triglycerides did not differ significantly between LNG implant acceptors (77.6 +/- 25.1 mg/dl) and DMPA injection acceptors (91.0 +/- 30.3 mg/dl). Serum concentrations of lipid fractions such as HDL-cholesterol and LDL-cholesterol in LNG implant acceptors were relatively low compared to those in DMPA injection acceptors. Since there was a comparable reduction in both total-and HDL-cholesterol levels in the LNG implant group, the ratio of total-to HDL-cholesterol, which is thought to be a factor in determining the risk of coronary artery disease, remained in the normal range (2 +/- 4.5). This suggests that the use of these two contraceptive methods with progestogens does not alter the risk of development of coronary artery disease.

Adolescent↗
PubMed1994

Ontogeny and distribution of Fc gamma receptors in the human placenta. Transport or immune surveillance?

The human fetus acquires maternal IgG via the chorioallantoic placenta. Utilising antibodies against 3 characterised subtypes of IgG receptor (Fc gamma R) expressed by human leucocytes, we show by confocal immunofluorescence microscopy that these molecules are also expressed by cells of the placenta. Fc gamma RI (CD64) is expressed by undifferentiated mesenchymal or fibroblast cells of 1st trimester and term chorionic villi. Punctate immunoreactivity for Fc gamma RII (CDw32) is found on capillary endothelial cells of term and 1st trimester villi. Fc gamma RIII (CD16) expression is observed in the trophoblast surrounding chorionic villi that forms the functional 'barrier' between mother and fetus. In 1st trimester villi this receptor is associated with a population of marginated vesicular inclusions of the syncytiotrophoblast. In term villi the receptor is concentrated in the apex of the syncytiotrophoblast, suggesting a possible role in the maternofetal transmission of passive immunity. All 3 subtypes of receptor are expressed by Hofbauer cells. We have been unable to demonstrate these receptors in cytotrophoblast cells. Results obtained using immunofluorescence and immunoelectron microscopic detection of endogenous IgG are consistent with the hypothesis that IgG is internalised into clathrin-coated pits and vesicles. Endogenous IgG was not demonstrable in cytotrophoblast cells. The significance of our inability to demonstrate IgG or specific receptor molecules for IgG in cytotrophoblast cells, and possible roles of Fc gamma receptor-bearing cells of the placenta are discussed.

Chorionic Villi↗
PubMed1993

The ventilatory response to carbon dioxide in high risk infants.

PURPOSE: To examine the ventilatory response to inspired carbon dioxide in infants considered to be at risk for sudden infant death syndrome or apnea. DESIGN: Clinical data measurement. SETTING: Infant apnea evaluation program of a university division of neonatology. PATIENTS: Fifty nine infants were full term characterized by the following diagnoses; siblings of infants who had died from sudden infant death syndrome (SIDS) (n = 7), apparent life threatening event (ALTE) (n = 24), apnea/cyanosis in the newborn nursery (n = 21), and controls. Sixty-nine infants were preterm and consisted of patients suffering from idiopathic apnea (n = 61), and bronchopulmonary dysplasia (n = 8). MEASUREMENTS: The ventilatory response to carbon dioxide was measured with a computerized waveform analyzer. MAIN RESULTS: Among full term infants no significant differences in the ventilatory slope in response to CO2 was seen. The range of mean slope was 19.4 +/- 7.6 in siblings of SIDS and 36 +/- 17 in control infants. Greater number of sibling of SIDS had slopes less than 20 ml/kg/min/mmHg in comparison to control infants. Sibling of SIDS had less increase in minute ventilation and inspiratory flow in response to CO2 administration in comparison to control infants. Preterm infants had similar slopes with a mean of 33 ml/kg/min/mmHg in infants with idiopathic apnea and 28 ml/kg/min/mmHg in infants with bronchopulmonary dysplasia. CONCLUSIONS: The large intragroup variability in the ventilatory response to inspired CO2, confirming previously reported data, comprises the benefit of this test. Thus, ventilatory response to CO2 administration is not useful in unselected patients at risk of SIDS or apnea.

Apnea↗
PubMed1993

Projections from the nucleus tractus solitarii to the spinal cord.

Projections from the nucleus tractus solitarii (NTS) to the spinal cord were demonstrated in the male Sprague-Dawley rat. In retrograde transport studies, a horseradish peroxidase conjugate or a fluorescent dye, FluoroGold, were injected into midcervical or upper thoracic spinal segments. Most solitariospinal neurons were multipolar or bipolar and located between the obex and spinomedullary junction. Solitariospinal neurons were concentrated in proximity to the ventral border of the solitary tract and extended dorsally into the intermediate division and ventrolaterally into the intermediate reticular zone (IRt) of the lateral tegmental field. This subgroup predominantly projects to midcervical spinal segments. A subset of small neurons was retrogradely labeled from cervical or thoracic spinal segments in the medial commissural nucleus and contiguous with a periventricular group surrounding the central canal. In anterograde transport studies, iontophoretic deposits of Phaseolus vulgaris leucoagglutinin were centered stereotaxically on sites in NTS identified by retrograde transport data. The lectin was incorporated by neurons of the solitary complex and transported bilaterally by axons that emerged from the nucleus and entered the reticular formation. The solitario-reticular (transtegmental) pathway irradiated diagonally across the IRt and extended caudally into the cervical lateral funiculus and spinal gray. A small periventricular-spinal pathway also descended longitudinally to the neuraxis. Solitariospinal neurons project to superficial lamina of the dorsal horn, laminae VII and X and ventral horn. The projections are predominantly contralateral to phrenic and intercostal motor nuclei and ipsilateral to the intermediolateral cell column. The solitariospinal projection represents the shortest route in the central nervous system, other than the local intraspinal reflex, through which first order visceral afferents signal cardiorespiratory and alimentary motor nuclei.

Animals↗
PubMed1993

Effect of cervical vagotomy on catecholaminergic neurons in the cranial division of the parasympathetic nervous system.

This study provides evidence of catecholaminergic neurons in the cranial division of the parasympathetic nervous system. Presumptive catecholaminergic preganglionic neurons in the dorsal motor nucleus of the vagus (DMX) were revealed by a clearcut depletion of intracellular catecholamine-synthesizing enzyme immunoreactivity induced by unilateral cervical vagotomy and identified on tissues immunocytochemically processed for tyrosine hydroxylase (TH), dopamine beta-hydroxylase (D beta H) or phenylethanolamine N-methyltransferase (PNMT). This experimental design was essential because of the recent failure in two species to reproduce data previously obtained in double-label (combined immunocytochemical-retrograde transport) studies. Vagotomy data confirmed three spatially-segregated populations of catecholaminergic visceromotor neurons in the DMX. These cell bodies were morphologically identical to preganglionic neurons observed on alternate tissues stained for Nissl substance or immunostained for choline acetyltransferase (ChAT), the enzyme biosynthesizing acetylcholine. Neurons in the central and medial DMX demonstrated fall-off of TH-like immunoreactivity (LI) ipsilateral to the vagotomy at levels caudal to the obex. This cell group is assumed to be predominantly dopaminergic since relatively few neurons at this level of the DMX expressed D beta H-LI and none were immunostained for PNMT. A second population of immunoreactive neurons, concentrated in the rostral-lateral region of the DMX, was depleted of D beta H-LI on the ipsilateral side but did not express PNMT. These visceromotor neurons may, therefore, biosynthesize noradrenaline and belong to the rostral pole of the A2 area. A third population of presumptive adrenergic vagal dorsomotor neurons in the rostral-medial DMX was depleted of TH-, D beta H- and PNMT-LI at levels of the ipsilateral nucleus anterior to obex. Patterns of depletion of cytoplasmic enzyme-immunoreaction product were identical in all cases irrespective of the site of the transection or the postoperative survival period. Quantitative analysis demonstrated statistically significant loss of immunolabeled neurons in rostral and caudal subgroups of the DMX on the side ipsilateral to the vagotomy. It is concluded that catecholaminergic processes in the vagus nerve, as previously identified by the aldehyde-induced histofluorescence method, may partly arise from the lower brainstem.

Animals↗
PubMed1993

Vasopressinergic mechanisms in the nucleus reticularis lateralis in blood pressure control.

We sought to determine whether arginine vasopressin (AVP) modulates arterial pressure (AP) by a receptor-mediated action in the nucleus reticularis rostroventrolateralis (nRVL). Immunocytochemical labeling with an antiserum against a synthetic AVP conjugate revealed a discrete although modest presumptive neuropeptidergic innervation of the nRVL. Electron microscopic analysis of vasopressinergic processes in the nRVL revealed that AVP-like immunoreactivity (AVP-LI) was primarily in axons and axon terminals. Immunoreactive terminals contained numerous small clear vesicles and large dense core vesicles and formed synapses with unlabeled dendrites. In the nRVL, retrograde transport-immunofluorescence data demonstrated close appositions between vasopressinergic beaded processes and a compact subambigual column of reticulospinal neurons labeled by deposits of cholera toxin beta-subunit into the thoracic spinal cord. Similar methods were used to define the origins of the AVP-afferent projection to nRVL. These retrograde transport-immunofluorescence studies demonstrated numerous retrogradely labeled neurons in the hypothalamus, including the paraventricular nucleus (PVN), after injections of a retrograde tracer, Fluoro-Gold into the ventrolateral medulla. However, double-labeled neurons were rare and confirmed a diffuse AVP afferent innervation of the sympathoexcitatory area. Microinjection of AVP into the nRVL in anesthetized rats produced a large dose-related increase in AP different from control at a dose of 1 pmol or higher. AVP injected intravenously elevated AP only at significantly higher doses. Microinjections of AVP into the nucleus tractus solitarii (NTS) had a smaller effect whereas into the caudal ventrolateral medulla exerted no effect on AP. Bilateral microinjections of an AVP antagonist, d(CH2)5[Tyr(Me)2]AVP into the nRVL produced no change in AP but blocked the increase produced by subsequent injections of AVP. An acute hemorrhage produced by withdrawal of 2 ml of blood from the femoral vein did not alter AP. However, bilateral microinjections of the AVP antagonist into the nRVL 5 min after hemorrhage decreased AP. In contrast, the AVP-antagonist injected intravenously after hemorrhage had no effect on AP. Our data suggest that under conditions demanding increased sympathetic drive to maintain AP, such as hemorrhage, a functional AVP receptor mechanism via terminals in the nRVL may be activated to restore normal levels of AP.

Animals↗