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Biomedical subjects

A Semplicini

Publications and source records attributed to A Semplicini.

At least 91 records · Page 5Linked to original sources
PubMed1989

Plethysmographic effects of doxazosin in essential hypertensive patients.

In the treatment of hypertensive patients with peripheral vascular disease, alpha 1-adrenoceptor blockers may be considered first-choice drugs since they reduce the total peripheral resistance and do not decrease the plasma volume. As a preliminary step, we investigated the plethysmographic effects of doxazosin (1-8 mg for 6 weeks) on calf flow in 32 uncomplicated hypertensive patients. Despite the fall in sitting and standing blood pressure (from 163 +/- 18/101 +/- 6 to 147 +/- 19/94 +/- 8 mmHg and from 162 +/- 18/107 +/- 9 to 145 +/- 18/95 +/- 8 mmHg, respectively; both P less than 0.001) the calf flow was not decreased at rest and after ischaemia. Resting resistance was not significantly reduced (from 49.5 +/- 35 to 38.9 +/- 33 mmHg/100 ml per min) but its fall was significantly correlated with the fall in mean blood pressure (rs = 0.35, P less than 0.05). These findings confirm that doxazosin may be useful in the treatment of hypertension complicated by peripheral artery disease.

Adrenergic alpha-Antagonists↗
PubMed1989

Kidney hemodynamics after ketone body and amino acid infusion in normal and IDDM subjects.

Little information is available on the hemodynamic response (renal reserve) of the diabetic kidney during an acute amino acid infusion, which has been shown to increase glomerular filtration rate (GFR) in normal humans. We recently found that the infusion of ketone bodies is able to raise GFR in both normal subjects and insulin-dependent diabetes mellitus (IDDM) patients. The aim of this study was to evaluate the renal reserve in 15 IDDM patients with a duration of diabetes of greater than 9 yr [8 with albumin excretion rate less than 15 micrograms/min (group 1) and 7 with albumin excretion rate greater than 100 micrograms/min (group 2)] and in 8 normal subjects during amino acid infusion (33 mumol.kg-1.min-1, Travasol 10% wt/vol solution containing 0.154 mM sodium chloride concentration; Travenol, Savage, MD) and during acetoacetic sodium salt (25 mumol.kg-1.min-1) infusion. Blood glucose was clamped at euglycemic levels. The infusion of sodium acetoacetate resulted in a 10- to 15-fold increase in circulating concentrations of ketone bodies, which were similar in magnitude in normal subjects and diabetic patients. The GFR peak increase above baseline after sodium acetoacetate infusion was 28% in normal subjects and 27% in group 1 and 19% in group 2 diabetic patients. The infusion of amino acid solution produced a three- to fivefold increase in plasma concentrations of amino acids in both normal subjects and diabetic patients. The GFR peak increase above baseline after amino acid infusion was significantly lower in diabetic patients (IDDM group 1: 5%, P less than .01; IDDM group 2: 6%, P less than .01) than in normal subjects (38%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Red blood cell membrane cation transport in normotensive psoriatics.

Psoriasis might be a widespread membrane disorder. To verify whether under the influence of psoriasis the red cell membrane cation metabolism is altered, we compared 46 psoriatics with 23 normotensive controls. A significant increase was observed in intracellular K+ content, in the maximal velocity of the Na(+)-K+ ATPase, of the Na(+)-K(+)-Cl- outward co-transport, of the Na+/H+ exchange, as well as in the outward passive permeability for Na+. No difference was seen between the two groups in Na+ content, Li+/Na+ exchange or in the passive permeability to K+. In 8 psoriatics treated with etretinate (10-75 mg/day for 1-36 months), Na(+)-K+ ATPase, Na(+)-K(+)-Cl- co-transport and the passive permeability for Na+ were not significantly different from controls. These results suggest that the primary abnormality might be an increased Na+ influx, in part through the Na+/H+ exchange, which is compensated by increased activity of outward transports, and confirm that the red cells are a useful model for the study of membrane transport in this disease. Our results indicate also that these membrane transport abnormalities can be corrected by etretinate treatment.

Adult↗
PubMed1989

[Volume of the extracellular liquid and renal function during short-term administration of angiotensin converting enzyme inhibitors in essential hypertension].

Short term angiotensin converting enzyme inhibition may induce a transient salt and water retention in patients with hypertension or heart failure. To verify the glomerular and tubular effects of short term converting enzyme inhibition, thirteen patients with mild to moderate essential hypertension (WHO I-II) were treated orally either with perindopril (4 mg o.d.) or captopril (25 mg b.i.d.) for one week. Both drugs reduced supine mean blood pressure significantly (p less than 0.01) (perindopril from 126 +/- 11 to 108 +/- 7 mmHg, mean +/- SD, and captopril from 132 +/- 12 to 121 +/- 16). Plasma volume (radio-iodinated albumin space) was unchanged while mean extracellular fluid volume (inulin space) increased although not significantly (from 5.05 +/- 1.32 l/sqm to 5.71 +/- 2.21 with perindopril and from 4.96 +/- 2.6 to 5.6 +/- 1.7 with captopril). Sodium clearance decreased (from 1.4 +/- 0.6 to 1.1 +/- 0.5 ml/min 1.73 sqm with perindopril, p less than 0.05, and from 0.97 +/- 0.44 to 0.88 +/- 0.51 with captopril, n.s.). In 9 patients (6 on captopril and 3 on perindopril) extra-cellular fluid volume increased simultaneously with reduction in glomerular filtration rate and in proximal tubule sodium re-absorption as well as an increase in distal tubule sodium reabsorption. In these patients the changes in proximal and distal tubule sodium reabsorption were significantly (p = 0.05) different from those of the patients with no extra-cellular fluid expansion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Tubular Na+ handling in type I insulin-dependent diabetics during saline and ketone body infusion.

It has been reported that patients with type I insulin dependent diabetes mellitus (IDDM) are characterized by reduced Na+ excretion during water immersion and saline infusion and abnormal glomerulo-tubular balance. Aims of the present study were therefore to investigate firstly the fractional tubular Na+ reabsorption during saline infusion to clarify the altered tubular site and secondly the glomerulo-tubular balance during acute increase of glomerular filtration rate induced by sodium acetoacetate infusion in IDDM. During saline and euglycaemic glucose clamp, after an overnight fast, glomerular filtration rate, renal plasma flow, filtration fraction and plasma sodium were 99 +/- 15 ml min-1 1.73 m-2, 452 +/- 109 ml min-1 1.73 m-2, 0.23 +/- 0.04 and 142 +/- 8 mmol l-1 (Mean +/- SD) in 10 type I insulin dependent diabetic patients and 96 +/- 18, 452 +/- 87, 0.21 +/- 0.02, 143 +/- 2 in five matched normal subjects, respectively. The lithium and sodium clearances were significantly lower in diabetic patients than in normal subjects (23 +/- 5 ml min-1 1.73 m-2 vs 28 +/- 6, p less than 0.05 and 1.1 +/- 0.4 vs 1.6 +/- 0.3, p less than 0.01 respectively). The fractional lithium reabsorption was greater (0.77 +/- 0.04 vs 0.72 +/- 0.03, p less than 0.05) and the distal fractional sodium reabsorption smaller (0.22 +/- 0.04 vs 0.27 +/- 0.03, p less than 0.01) in the diabetic patients compared to the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetoacetates↗
PubMed1989

[Erythrocyte Li/Na countertransport and correlated variables in a randomized sample of population].

A genetically determined alteration of the cell membrane sodium metabolism may play a role in the pathogenesis of essential hypertension. The most consistent finding in patients with essential hypertension is an increased red blood cell Li/Na exchange (countertransport). It is genetically determined but it is also associated to potentially confounding variables (body weight, race, age and so on). The present study investigates the relationship between red cell Li/Na countertransport and various potentially confounding variables in a random sample of the population. It shows that this membrane cation transport system is increased in males compared to females and significantly correlated to body mass index in males and to blood pressure, alcohol consumption and, negatively, to urinary calcium excretion in females. Since body weight and alcohol consumption are correlated to blood pressure in several epidemiological studies, it can be hypothesized that they influence blood pressure control through an alteration of the cell membrane sodium transport.

Adult↗
PubMed1988

Red blood cell sodium and potassium fluxes in psoriatic patients.

Psoriasis might be a widespread membrane disorder. Therefore, the red blood cell sodium, potassium and lithium outward fluxes (through Na-K-ATPase, Na-K-Cl co-transport, Li-Na countertransport and passive permeability), as well as the Na and K content, were studied in 31 psoriatic patients and 23 normal controls. A significant increase in intracellular potassium content, in the maximal velocity of the Na-K ATPase and of Na-K-Cl co-transport as well as in the outward passive permeability for Na were found in the psoriatic patients compared with controls. On the contrary, no differences were observed in sodium content, Li-Na countertransport and passive potassium permeability between the two groups. These results are compatible with a selective increase in inward, as well as outward, membrane permeability to sodium, which is compensated for by increased activity of the Na-K pump, and of the outward Na-K-Cl cotransport with a secondarily increased erythrocyte potassium content. They indicate that the red blood cell might be a useful model for the study of membrane transport in psoriatics.

Adult↗
PubMed1988

Genetic differences in lithium-sodium exchange and regulation of the sodium-hydrogen exchanger in essential hypertension.

The elevation of Vmax of red cell Li/Na exchange in some hypertensives and in their normotensive offspring is mainly accounted for by genetic factors. In order to understand the pathophysiological meaning of this finding, we have studied if it is an operational mode of H/Na exchange, a transport system involved in the regulation of cell pH in vascular and kidney cells. To define the relationship of the Li/Na exchange to the H/Na exchange pathway, we have investigated the kinetic effects of internal and external H+ on H/Na, H/Li, and Li/Na exchange. These three exchange modes have highly asymmetric affinities for H+ much greater than Li+ greater than Na+, are activated by internal H+ (Hi) with a high "Hill coefficient" (n = 2.5), and competitively inhibited by external H+ (Ho). Moreover, cell Li activates H/Na exchange while being transported by Li/Na exchange at a lower rate than Hi. These observations support the conclusion that Li/Na exchange is a mode of operation of H/Na exchange. Li+ discriminates better than cell H+ between regulatory and transport sites in red cells of normotensive subjects. Kinetic studies of H/Na exchange in red cells of hypertensive subjects with high Li/Na exchange indicate that the Vmax of both pathways are not linearly related. Thus, Li/Na exchange does not measure the number of Na/H sites but assesses the occupancy of an internal site. We found that H/Na exchange in hypertensive subjects has a reduced Hill coefficient for the cell pH dependence of Na influx, which is interpreted as a defective Hi regulatory site.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Time course of changes in blood pressure, aldosterone and body fluids during enalapril treatment: a double-blind randomized study vs hydrochlorothiazide plus propranolol in essential hypertension.

Aldosterone suppression is said to play a major role in the long term hypotensive efficacy of angiotensin converting enzyme inhibitors. However, in previous reports from other laboratories, plasma volume has been found mostly increased and sodium balance sometimes positive. The effects of the angiotensin converting enzyme inhibitor enalapril (10-40 mg/day, p.o., for 6 weeks) on blood pressure, body fluid volumes, renal function and plasma aldosterone were compared to those of hydrochlorothiazide (50 mg/day, p.o.) alone for 2 weeks and in association with propranolol (80-160 mg/day, p.o.) for 4 more weeks during a randomized double-blind parallel study in 14 essential hypertensives. Hydrochlorothiazide alone and in combination with propranolol induced slight and not significant change in either blood pressure and body fluids. The maximum hypotensive response to enalapril was achieved only after 2 weeks of continuous treatment possibly because after 1 week the hypotensive efficacy was lessened by a significant (P less than 0.05) fluid retention secondary to a transient and not significant fall in renal perfusion. At this time aldosterone was not significantly changed compared to pretreatment values. After 6 weeks on enalapril, blood pressure was significantly reduced, plasma aldosterone further but not significantly decreased and extracellular fluid volume was normal. These findings indicate that aldosterone suppression contributes to the blood pressure lowering effect of enalapril by offsetting the salt and water retention observed on starting treatment and due to direct vasodilation.

Adult↗
PubMed1986

Captopril-stimulated renin in the diagnosis of restenosis after percutaneous transluminal renal angioplasty.

Recurrence of hypertension is reported in a considerable percentage of renovascular hypertensive patients treated by percutaneous transluminal angioplasty (PTRA); among the possible mechanisms for these failures, restenosis of the renal artery is the only correctable one. Since captopril stimulates renin secretion to a greater extent in renovascular than in essential hypertensive patients, we determined if it could be used to unmask significant restenosis in the patients with hypertension recurring after PTRA. Follow-up study was performed in 28 patients treated with PTRA. We found that captopril caused a greater increase in peripheral plasma renin activity in 8 of 8 cases who had recurrence of hypertension and restenosis than in 13 of 15 of the patients who did not. We suggest that the determination of captopril-stimulated renin may provide a useful, simple and economical tool for the detection of restenosis after PTRA.

Adolescent↗
PubMed1985

Percutaneous transluminal renal angioplasty: influence of complications on long-term blood pressure results.

Natural history and outcome of percutaneous transluminal renal angioplasty (PTRA) in renovascular hypertension (RVH) were assessed retrospectively in 52 patients in whom 62 PTRAs were successfully performed. Complications were observed in 16 patients: prolonged and extensive arterial spasms in eight, severe intimal dissection of the main renal artery in five, arterial thrombosis at the site of PTRA in two and acute deterioration of renal function in one. All the complications cleared up with medical treatment except for one major dissection occluding the distal branches, which required surgery. According to the Co-operative Study, after 1-5 years of follow-up, 21 patients (40.4%) were cured, 27 (51.9%) improved and four (7.7%) did not improve. The long-term results on blood pressure in both uncomplicated and complicated cases were better in fibrodysplasia (61.5% cured, 34.6% improved and 3.8% not improved) than in atherosclerosis (17.4% cured, 69.6% improved and 13% not improved). In the last 21 PTRAs performed, in which verapamil (200-1500 micrograms) was given as a bolus injection into the stenotic artery before dilatation, the complication rate was significantly lower. It is concluded that PTRA is an effective treatment for RVH; complications occurred in 25.8% of PTRAs and resulted in poor control of blood pressure in atherosclerosis but not in fibrodysplasia; premedication with verapamil into the stenotic renal artery reduced the complication rate.

Adult↗
PubMed1985

Intra-erythrocytic sodium content in normotensive offspring of normotensive and hypertensive subjects: an epidemiological study.

An increase in intra-erythrocytic sodium (IENa) content has been proposed as a genetic marker of essential hypertension. Intra-erythrocytic sodium was studied using hypotonic lysis and flame photometry after four washings with isotonic MgCl2 in 240 normotensive subjects (aged 10-45 years) on a free diet with (F+, 121 patients) or without (F-, 119 patients) hypertensive parents, recruited from a random sample of the general population. Systolic blood pressure was significantly higher in males F+ than in males F- (130 +/- 2 versus 125 +/- 2 mmHg, mean +/- s.e.m., P < 0.05), while IENa did not differ. In contrast, intra-erythrocytic potassium content (IEK) was significantly lower and red cell sodium potassium (Na:K) ratio significantly higher in F+ than F-. This might reflect decreased NaK pump activity, or increased membrane permeability to cations which causes increased K leakage. No differences in blood pressure, IENa or IEK showed in female F+ versus F-. It is concluded that IENa is not a genetic marker of hypertension, and that it is probably influenced by exogenous factors. Being associated with differences in blood pressure, the abnormalities of IEK and Na:K ratio might be pathogenetically linked to an early increase in blood pressure.

Adolescent↗