摘要:

SUMMARY The vasodepressor response to single and multiple oral doses of hydralazine, 1 mg/kg, was studied in hypertensive patients. The concentration of bydralazbe in plasma was measured both by a newly developed specific and a nonspecific assay similar to those used in previous studies. Acetylator phenotype was determined following oral sulfamethazine. Plasma hydralazine concentration peaked at 1 hour after administration and was undetectable 2 hours later. Apparent hydralazine was present in plasma in higher concentration and for a longer duration than hydralazine. The peak decreases in blood pressure (BP) were proportional to plasma hydralazine concentration following administration of both single and multiple doses and were substantially maintained for 8 hours. In contrast there was no significant correlation between decreases in BP and apparent hydralazine concentrations. The plasma concentration of hydralazine after a standard oral dose varied by as much as 15-fold among individuals and was lower in rapid than slow acetylator phenotype patients. The BP responses were positively correlated with plasma hydralazine concentrations and inversely correlated with acetylator indices. Low plasma concentrations may account for poor responses of some patients to conventional oral doses of hydralazine. The applicability of acetylator pbenotyping for individualization of hydralazine dosage regimens merits further evaluation.

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SUMMARY This study examined characteristics of paracelhilar and plnocytotic permeability pathways across the middle cerebral artery endothellum of 12- to 16- month-old spontaneously hypertensive rats (SHR). Interendothelial junctions in SHR, like those of age-matched Wistar-Kyoto controls, were impermeable to lanthanum and horseradish peroxidase (HRP) tracers. Freeze-fracture preparations revealed that interendothelial junctions of chronically hypertensive rats are characterized by a twofold increase over controls in the number of tight junctional strands and the mean apical-basal depth. It is bettered that this tight junctional hypertrophy may function to increase adhesive forces between neighboring eadothelial cells, and may play a role in the prevention of hypertension-induced paracellular permeability increases. Morphological and tracer studies of pinocytotic pathways indicated that, in the middle cerebral artery, endothelial vesicular transport activity is not increased during chronic hypertension. No evidence was found to indicate the presence of transendothelial permeability channels across control or hypertensive arterial endotbdium. Thus, Increased transendothelial permeability, commonly observed in acute hypertension, does not appear to occur during chronic hypertension, at least in the middle cerebral artery. Our findings suggest that the arterial endothelium may undergo structural (tight junctional) adaptation in response to prolonged hypertension.

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SUMMARY Nonlnrasive portable blood pressure systems (PBPS) are typically based on the Korotkov sound technique. The performance of related Korotkov sound analysis techniques was assessed in PBPS data obtained from nine normotensive and nine hypertensive men. Multiple-seated PBPS measurements were taken, each following 1 minute of quiet rest, moderate walking, and stair climbing; each PBPS measurement was accompanied by a simultaneous auscultatory measurement in the same arm. In subsequent manual PBPS data analysis, PBPS systolic and diastolic BPs were within 4 mm Hg of corresponding auscultatory BPs 86% and 88% of the time; BPs following rest and walking showed greater accuracy, while those following stair climbing were less accurate. Interestingly, automated analysis of diastolic PBPS data (using selective bandpass filtering, amplitude normalization, and comparator decision ratios) provided a level of accuracy similar to that obtained from manual data analysis. Overall, both manual and automated Korotkov sound analysis techniques can provide BP results that agree quite well with auscultatory determinations.

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SUMMARY Direct intravital microscopy was used to analyze microclrculatory changes in the exteriorized spinotrapezius muscle of spontaneously hypertensive rats (SHR). The animals were anesthetized with a mixture of chloralose-urethane, and measurements made pressure, flow, and resistance in vessels ranging in size from 50 to 5 Mm. Tbe vascular changes in SHR were compared with matched Wistar-Kyoto (WKY) strain animals for both young (5-6 weeks old) and mature (12-13 weeks) rats. Distinctive changes in tbe distribution and levels of pressure, flow, and resistance were seen in tbe entire mlcrovascular network during both stages of the syndrome. There was no significant increase in the resistance of the conduit arteries just proximal to tbe muscle proper. Blood pressure in hypertensives was brought down to normal and even below normal at the level of the capillaries and postcapiiiaries irrespective of tbe height the pressure in the major artery supplying the muscle. The greater drop in pressure across the arteriolar branchings of tbe hypertensives was seen as early as at 5-6 weeks of age; this difference Is much more striking in 12-13 week-old mature hypertensives. The reduction in pressure was proportionately greatest the region of smallest (10-15 /im) precapillaries hypertensives. Resistance values were below normal in the confluent capillaries and postcapiiiaries in both young and mature hypertensives. Volumetric flow, which was marginally higher throughout the arteriolar branchings, fell below normal on the postcapillary side. Since an increased resistance developed at an early age (5-6 weeks) in all of the microvessels on the precapillary side, tbe suggestion is advanced that hypertension associated with a generalized effect on tbe muscular arterioles below 30 urn, an effect that becomes more pronounced with time and at 12-13 weeks begins to involve larger sized arterioles (30-40 pm wide).'

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SUMMARY The effect of continuous Intrarenal Infusion of noreplnephrine, Uoproterenol, and metboxaraine on renin release was studied in the uninephrectomized conscious dog. Chronic intrarenal infusion of noreplnephrine produced a biphasic curre of plasma renin actirity (PRA) and a sustained 25 mm Hg increase in mean arterial pressure (MAP). The initial increase in PRA peaked at 3 hours, after which PRA returned to control lerels. Alphaor beta-adrenergic antagonists did not attenuate the initial rise in PRA. The PRA Increased again after 48 hours of chronic intrarenal noreplnephrine Infusion and remained derated thereafter. The second rise in PRA was increased by 30% with alpha-adrenergic blockade. Chronic intrarenal isoproterenol administration produced a similar increase in PRA, which peaked at 3-5 hours and then returned to control levels. In contrast to norepinephrine, chronic Isoproterenol administration did not result in a second increase in PRA. At the end of the chronic Isoproterenol Infusion period, beta-adrenergic receptor refractoriness was demonstrated, as PRA did not increase significantly in response to a fourfold increase in the dose of isoproterenol. An Increase in PRA was produced by acute Intrarenal infusion of metboxamine. This increase in PRA was blocked by pbentolamlne, suggesting a vascular alpha-adrenergic receptor-mediated release of renin.

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SUMMARY To compare the sodium-retaining action and the effect on blood pressure (BP) of certain steroids, nine nonnotensive subjects were given fludrocortisone0.3ragorally twice a day (b.i.d.), five received deoxycorticosterone acetate (DOCA) 10ragIM b.i.d., and this was compared to the effect of fludrocortisone or DOCA plus prostaglandin inhibition (PI) or PI given alone. PI was accomplished with either indomethacin 50 mg or ibuprofen 400 mg every 6 hours. All patients received 250 mEq Na+daily. Fludrocortisone alone caused a cumulative Na + balance of 305 ± 46 (SE) mEq and weight gain 2.5 0.1 kg with escape by Day 7. Mean blood pressure (MAP) increased 9 ± 2 mm Hg in both supine and standing positions by Day 8. When fludrocortisone was continued for 16 days, BP rose 14 ± 1 and 11 ± 1 mm Hg respectively. DOCA caused similar Na+retention of 485 ± 125 mEq, weight gain 2 kg, and escape by Day 7; however, no change in BP was observed. PI alone caused retention of 125 ± 49 mEq, weight gain 1 kg, and escape by Day 4, but no change in BP. In contrast, fludrocortisonewith PI added on Day 9 increased BP 21 ± 2 supine (p< 0.01) and 19 ± 2 mm Hg standing (p< 0.001) compared with fludrocortisone alone, but no greater change in Na + or weight was observed. DOCA plus PI also resulted in no greater Na + retention or change in weight than DOCA alone; however, BP increased from 86 ± 3 to 98 ± 2 mm Hg (p< 0.01). Similar suppression in PRA and aldosterone was noted in all of the study groups. We conclude that: 1)fludrocorticonehas a pressor action in normal humans Independent of its effect on sodium balance; 2) DOCA, a pure mineralocorticoid, does not alter BP when given for a period of weeks; 3) PI in normal humans causes some retention sodium, but does not alter BP; 4) prostaglandin synthesis inhibitors potentiate the pressor action offludrocortisoneand raise BP in DOCA-treated humans, suggesting that vascular prostaglandins play a modulating role in BP control.

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID

ISSN:0194-911X    

出版商:OVID    

年代:1981

数据来源: OVID