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Biomedical subjects

F Fyhrquist

Publications and source records attributed to F Fyhrquist.

At least 109 records · Page 6Linked to original sources
PubMed1989

Experimental ductus arteriosus: the relationships of atrial pressure, dilatation and flow with ANF secretion.

The design of the study was to determine whether an increased blood flow as seen in shunt lesions could serve as a stimulus for the secretion of atrial natriuretic factor (ANF). Since atrial pressure, flow, and dilatation are closely related, an experimental ductus arteriosus model was utilized, in which acute changes of flow are assumed not to dilate the left atrium. In six dogs, a Dacron graft was constructed between the main pulmonary artery and the innominate artery. Constricting and releasing the tape around the graft adjusted the amount of "ductal" shunting. The total pulmonary flow and the shunt flow were measured by electromagnetic-flow transducers around the aortic root and around the graft. Plasma ANF concentration was measured from both cardiac atria. The size of the left atrium was determined from echocardiographic measurements made from a short-axis view. The total pulmonary flow varied between 1.2 and 5.8 1/min. The highest measured ANF was 396 pg/ml, and this was from the left atrium when the pressure was 18 mmHg, the highest left atrial pressure recorded. The highest right atrial pressure (5 mmHg) also correlated with the highest right-atrial level of ANF (366 pg/ml). The right atrial pressure had a significant correlation with plasma ANF concentration (R = 0.43, p less than 0.05). Pulmonary flow and plasma ANF concentration did not correlate; neither did left atrial size and ANF levels in 16 flow states where the size was measured. In the absence of atrial dilatation there was minimal stimulus for ANF secretion. A transient increase of left atrial pressure, without a concomitant significant atrial dilatation, did not serve as a significant stimulus for ANF secretion.

Animals↗
PubMed1989

Vasodilator properties of atrial natriuretic factor: a comparison with nitroglycerin, nitroprusside, and phentolamine during cardiopulmonary bypass.

Thirty-five patients scheduled for coronary artery surgery were studied during hypothermic cardiopulmonary bypass (CPB) to compare the arteriolar and venodilator properties of a bolus dose of atrial natriuretic factor (ANF), 100 micrograms, with those of nitroglycerin, 200 micrograms, sodium nitroprusside, 120 micrograms, phentolamine, 3 mg, and placebo. A decrease observed in mean arterial pressure was used as an indicator of a decrease in systemic vascular resistance (arteriolar dilation), while a decrease in reservoir blood volume of the CPB circuit was considered to indicate an increase in venous capacitance (venodilation). All vasodilators decreased mean arterial pressure, and there was no difference in the maximal decrease of the pressure between the drugs. However, the decrease caused by ANF appeared later than that caused by the other vasodilators and lasted longer than with nitroglycerin and sodium nitroprusside. Nitroglycerin and sodium nitroprusside decreased reservoir blood volume, while ANF and phentolamine had no effect. It is concluded that ANF is an arteriolar dilator with a time profile of its effect differing from those of nitroglycerin, sodium nitroprusside, and phentolamine. ANF seems to have no venodilator activity in patients undergoing hypothermic CPB.

Atrial Natriuretic Factor↗
PubMed1989

Attenuated diuretic and natriuretic effects of atrial natriuretic peptide in rats with heart failure.

Plasma levels of atrial natriuretic peptide (ANP) and renal responses to ANP were examined in rats with chronic cardiac failure produced by coronary artery ligation and in sham-operated controls. Plasma ANP levels were elevated in the rats with severe cardiac failure as compared with the controls (P less than 0.001). ANP injections at the doses of 1, 5, 25 and 50 micrograms/kg increased water and sodium excretion significantly at all but the lowest dose in the controls; only the two largest doses caused clear diuresis and natriuresis in the heart failure group. The diuretic and natriuretic effects of ANP were significantly weaker at the doses of 5 and 25 micrograms/kg in the rats with heart failure as compared with the controls. We conclude, that natriuretic and diuretic effects of ANP are attenuated in this chronic heart failure mode.

Animals↗
PubMed1989

Effects of licorice on plasma atrial natriuretic peptide in healthy volunteers.

Ingestion of licorice, 100 g daily for 8 weeks, caused a rise in 81% in plasma atrial natriuretic peptide (ANP) concentration in 12 healthy subjects. Mean body weight increment (1.6 kg) correlated with the increase in plasma ANP (r = 0.59; P less than 0.01). The plasma concentrations of antidiuretic hormone, aldosterone, and plasma renin activity decreased. All these hormonal effects, reflecting retention of sodium and fluid volume, were probably due to the known mineralocorticoid properties of licorice. Blood pressure increased transiently and two subjects developed reversible hypertension. The rise in plasma ANP concentration during ingestion of licorice may be considered a physiological response to prevent fluid retention and development of hypertension.

Adult↗
PubMed1989

Long-term prognosis of surgical treatment of renovascular hypertension.

During the period 1974-1986, 71 patients were operated on for renovascular hypertension. Forty-eight patients had atherosclerotic disease and 23 patients had fibromuscular dysplasia. There was no operative mortality. Fourteen patients died during the follow-up, 12 of them from cardiovascular causes. The 57 surviving patients were reexamined with a mean follow-up of 7 years. The relative cumulative 5- and 10-year survival rates in all patients were 79% and 55%, respectively. At follow-up, seven (19%) of the atherosclerotic patients were classified as cured, 22 (59%) as improved and eight (22%) as failures. In the patients with fibromuscular dysplasia, 12 (60%) were normotensive without medication, and six (30%) were improved. The relative 5-year survival rates in these aetiological groups were 73% and 90%, respectively. Only complete cure of hypertension by surgery predicted a good outcome, whereas very similar survival curves were found in the improved and failed groups. This could be due to a higher incidence of target organ changes before surgery in the latter groups. A positive blood pressure response to long-term converting-enzyme inhibition correlated well with the response to surgery. Renal venous renin studies correctly predicted long-term outcome of surgery in 78% of the patients studied, but require careful preparation of the patients and interpretation of results.

Adult↗
PubMed1989

High serum erythropoietin levels are normalized during treatment of congestive heart failure with enalapril.

Eighteen patients with dilated cardiomyopathy (three female, mean age 57 years), were treated for 48 weeks with enalapril added to digoxin and diuretic therapy for congestive heart failure of New York Heart Association (NYHA) functional class II (three patients). III (eight patients) and IV (seven patients), respectively. Serum levels of erythropoietin (EPO) were raised at the start (37 +/- 12.8 pmol 1(-1); mean +/- SD) and were normalized during enalapril treatment (17.5 +/- 9.9 pmol 1(-1) at 48 weeks; P less than 0.001). Serum EPO correlated at the start with NYHA functional class (r = 0.68; P less than 0.05). Normalization of elevated serum EPO concentrations during treatment with enalapril paralleled clinical and haemodynamic improvement, and probably reflected relief from renal hypoxia.

Adult↗
PubMed1989

Beneficial effects of erythropoietin on haematological parameters, aerobic capacity, and body fluid composition in patients on haemodialysis.

Eleven patients on haemodialysis were treated with erythropoietin (EPO), 50-200 U kg-1 once to three times a week, for up to 1 year. After outset of EPO all patients became transfusion-independent. Four patients did not reach the target haemoglobin (Hb) level 100 g l-1 in 5 months. These patients had higher serum concentrations of aluminium (225 +/- 87 micrograms l-1, mean +/- SD) than the responding patients (55 +/- 56 micrograms l-1). Addition of desferrioxamine to treatment with EPO resulted in a rapid rise in Hb values in these patients. Thus, aluminium may inhibit EPO responsiveness. All patients were iron overloaded. Serum ferritin levels declined in all but one patient with secondary haemochromatosis. In exercise tests the aerobic capacity and oxygen uptake increased during EPO therapy. Peak oxygen consumption (Vo2 peak), oxygen pulse, oxygen uptake at anaerobic threshold (AT) and total work output (W max) increased 19%, 36%, 26% and 24%, respectively. Lean body mass (LBM) increased by 8%. Taken together, all clinical EPO effects measured appeared clinically favourable.

Adult↗
PubMed1989

No effect of short term angiotensin II infusion on plasma renin substrate levels in man.

We studied the effect of angiotensin II (A-II) infusion (4 ng/kg BW.min) on plasma renin substrate (RS) levels and PRA in five normal men during normal, diuretic-stimulated, and enalapril-interrupted function of the renin-angiotensin system. A-II infusion increased (15-25%) both systolic and diastolic blood pressure in the normal state and during angiotensin-converting enzyme inhibition, whereas the increase during diuretic-stimulated renin-angiotensin system function was less. The plasma RS concentration was measured by both direct and indirect RIA. The mean basal plasma RS levels, measured with direct assay, were 1516 +/- 150 (SE) in the normal state, 1566 +/- 150 after diuretic administration, and 1650 +/- 133 nmol/L after enalapril administration. The corresponding mean basal plasma RS levels measured with the indirect assay were 1073 +/- 100, 1031 +/- 57, and 902 +/- 78 nmol/L, respectively. Plasma RS levels did not change during or after the A-II infusions, whereas PRA decreased significantly in all experimental conditions. The results suggest that A-II exerts no direct stimulatory effect on hepatic release of RS. Thus, A-II appears not to be important in the short term regulation of plasma RS levels.

Adult↗
PubMed1989

[Endothelin].

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Animals↗
PubMed1988

Atrial natriuretic peptide in congestive heart failure.

Release of atrial natriuretic peptide (ANP) appears to be a compensatory response in congestive heart failure (CHF) that may counterbalance the adverse effects of stimulated renin-angiotensin and sympathetic nervous systems. We observed increased plasma ANP concentrations in CHF patients in New York Heart Association functional classes II to IV. The fact that such responses already become evident when a patient is in New York Heart Association class II supports the concept that ANP release may counteract the detrimental effects of stimulation of renin and the sympathetic nervous system even in the early phases of heart failure by promoting diuresis and natriuresis, as well as vasodilatation, thus reducing both pre- and afterload. When CHF is severe, however, the counterbalancing effects of ANP may be offset by vasoconstriction and fluid and sodium retention.

Atrial Natriuretic Factor↗
PubMed1988

Increased levels of immunoreactive plasma renin substrate during infectious peritonitis in patients on continuous ambulatory peritoneal dialysis.

1. Renin substrate (RS) and certain serine protease inhibitors share structural homology. Previous studies have shown that RS may be an acute-phase protein. 2. This prospective study was carried out to monitor plasma RS and other components of the renin-angiotensin system and acute-phase proteins during infectious peritonitis in patients on continuous ambulatory peritoneal dialysis. 3. RS was measured by both an enzymatic assay and a direct radioimmunoassay. An enzymatic assay measures intact RS only, whereas a direct radioimmunoassay measures both intact RS, capable of releasing angiotensin I and des-(angiotensin I)-RS, the residue of RS after cleavage of angiotensin I. 4. RS determined by direct radioimmunoassay increased (P less than 0.001) during acute inflammation (peritonitis), whereas neither RS measured enzymatically nor plasma renin activity changed significantly. 5. Our observation points to RS being an acute-phase protein in man. 6. Serum angiotensin-converting enzyme was measured by both an enzymatic and an inhibitor-binding assay. Both assays showed decreased levels of angiotensin-converting enzyme during acute inflammation.

Acute-Phase Proteins↗
PubMed1988

Hemodynamic effects of alpha-human atrial natriuretic peptide in healthy volunteers.

The hemodynamic effects of synthetic alpha-human atrial natriuretic peptide (alpha-hANP) were evaluated in a double-blind, placebo-controlled study with echocardiography and systolic time intervals in 11 healthy volunteers. During an infusion of alpha-hANP for 30 min, when plasma ANP concentration increased to a peak level of approximately 300 pg/ml, an increase occurred in diuresis (+174%, p less than 0.01 vs. placebo) and natriuresis (+148%, p less than 0.05). Heart rate increased (+10%, p less than 0.05), but the mean arterial pressure remained unchanged. The left ventricular end-diastolic diameter was reduced (-3%, p less than 0.01), as was the left ventricular end-systolic diameter (-11%, p less than 0.001). Total peripheral resistance (-12%, p less than 0.05) and midsystolic circumferential wall stress (-16%, p less than 0.05) decreased, while cardiac output increased (+15%, p less than 0.05), as did fractional shortening (+15%, p less than 0.001). Within 30 min postinfusion, all differences between the ANP and placebo treatments had disappeared. No significant difference between the treatments was observed in preejection period or preejection period/left ventricular ejection time ratio. In conclusion, when administered as a short infusion, alpha-hANP causes peripheral arterial vasodilation and thus, by reducing left ventricular afterload, improves the pump function of the heart. Venous vasodilating effect of alpha-hANP may contribute to the decrease in left ventricular preload, but a diuresis-induced reduction in circulating intravascular volume may also be influenced.

Adult↗
PubMed1988

Plasma atrial natriuretic peptide in cardiac transplant recipients. A prospective study.

Cardiac transplantation in 10 patients with congestive heart failure resulted in reduction of high plasma concentrations of atrial natriuretic peptide (ANP), preoperatively five-fold above normal, to a level two-fold above normal, which was maintained throughout a 12-week follow-up period. Cardiac function was normalized in all patients. Transient increases in plasma ANP, in four cardiac recipients 3-10-fold their basal levels, could neither be related to rejection episodes nor to cardiac dysfunction, but rather to signs of fluid and sodium retention. High plasma ANP levels in cardiac transplant recipients suggest that the capacity to secrete ANP is preserved in the transplanted heart.

Adolescent↗
PubMed1988

Atrial natriuretic peptide and atrial pressures in newborns with transposition of the great arteries.

The relation of atrial pressure to atrial plasma concentration of atrial natriuretic peptide (ANP) was studied in four newborns undergoing catheterization because of transposition of the great arteries. In three patients, mean left atrial pressure clearly exceeded right atrial pressure (12 +/- 7 vs. 2 +/- 3 mmHg; mean +/- SD). In one patient mean atrial pressures were identical (4 mmHg). In all patients the ANP concentration in the left atrium exceeded that of the right (833 +/- 464 vs. 415 +/- 366 pg/ml; mean +/- SD). There was a significant (r = 0.97; p less than 0.01) correlation between pressure and ANP concentration in the left atria. In the right atria, no linear correlation existed between pressure and ANP concentration. ANP concentration in the left atrium decreased after a lowering of the left atrial pressure by atrial septostomy. In these patients, the left atrium seems to be the main source of circulating ANP.

Atrial Natriuretic Factor↗
PubMed1988

Cord plasma vasopressin, erythropoietin, and hypoxanthine as indices of asphyxia at birth.

To assess the value of cord plasma arginine vasopressin (AVP), erythropoietin (EP), and hypoxanthine (HX) as indices of asphyxia, we studied 62 infants of mothers with preeclampsia, 34 acutely asphyxiated infants, with 5-min Apgar score less than or equal to 6 and/or umbilical arterial pH less than or equal to 7.05, and 38 control infants. Umbilical arterial AVP in the asphyxia group (geometric mean; 95% confidence interval: 180; 92-350 pg/ml) was higher than in the control group (23; 8-66, p = 0.002) and correlated with umbilical arterial pH (r = -0.447, p = 0.028). AVP levels in the preeclampsia group did not differ from controls. Cord venous EP was higher in infants delivered by elective cesarean section from women with severe preeclampsia (115; 75-177 mU/ml, p less than 0.001) than in control infants (23; 18-27); in the whole group EP correlated with pH (r = -0.493, p less than 0.001). EP in the asphyxia group was similar (46; 35-65) to controls (40; 33-47) and did not correlate with pH. Cord arterial HX in the preeclampsia group was similar to controls (12.3; 9.5-16.0 mumol/liter), but elevated in the asphyxia group (23.7; 17.6-31.8, p = 0.001), in which HX correlated with pH (r = 0.558, p = 0.008) and AVP (r = 0.588, p = 0.005). EP did not correlate with AVP or HX in any group, nor did any of the variables correlate with the Apgar score. We conclude that cord plasma AVP and HX reflect acute asphyxia, whereas EP is elevated after more prolonged hypoxia.

Apgar Score↗