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Biomedical subjects

S G Chrysant

Publications and source records attributed to S G Chrysant.

At least 73 records · Page 4Linked to original sources
PubMed1981

Magnesium and potassium interrelationships, experimental and clinical.

1) Coexisting Mg and K deficiency may occur with greater frequency than has been previously appreciated. 2) Profound hypokalemia, or refractoriness to K repletion or coexisting hypokalemia and hypocalcemia should suggest the possibility of concurrent Mg and K depletion. 3) The identification and treatment of concurrent K and Mg depletion is especially important in patients with congestive heart failure because of problem of digitalis toxicity. 4) We believe that the role of magnesium in optimizing cardiac function remains to be elucidated, identification and treatment of coexisting Mg and K depletion will be facilitated by making serum Mg a routine electrolyte determination together with Na, K, Cl, CO2.

Adult↗
PubMed1981

Effects of diet on exaggerated natriuresis in hypertension.

The effects of high and low salt diet on exaggerated natriuresis after volume expansion were examined in two groups of hypertensive patients, 6 with labile and 6 with fixed uncomplicated essential hypertension. Fixed hypertensives eliminated the administered salt-load faster than the labile hypertensives, and diet had no effect on the exaggerated natriuresis of both groups. No association was observed between plasma renin activity and natriuresis in both groups of patients. We conclude that, 1) diet did not affect the saline-induced natriuresis in hypertensive patients, 2) there was no apparent association between plasma renin activity and exaggerated natriuresis in hypertension, 3) other factors such as the capacitance system and vasopressin may play an important role in volume expansion natriuresis, especially in fixed hypertensives.

Blood Pressure↗
PubMed1981

Hemodynamic correlates of autonomic reflexes in patients with labile and fixed hypertension.

the autonomic sympathetic reflexes to sustained handgrip, upright tilt and the Valsalva maneuver, were tested in 26 patients with labile and 26 with fixed essential hypertension. Sustained handgrip increased systolic (SAP), diastolic (DAP) and mean arterial (MAP) pressure, heart rate (HR), cardiac index (CI), tension time index (TTI) (p less than .01), and had no effect on total peripheral resistance index (TPRI) and left ventricular ejection rate index (LVERI) in both groups of patients. However, the response to upright tilt and the Valsalva maneuver was different in the two groups. Upright tilt in labile hypertensives increased DAP, MAP, HR, and TPRI (p less than .001); decreased CI, stroke index (SI) and LVERI (p less than .01) and had no effect on SAP. In fixed hypertensives, it decreased SAP, MAP, CI, SI and LVERI (p less than .001); increased HR (p less than .01) and had no effect on DAP, and TPRI. The diastolic pressure overshoot of the Valsalva maneuver was attenuated in fixed hypertensives compared to labile (p less then .001). Additionally, when the percent changes from control in DAP, MAP, HR and TPRI to sustained handgrip and upright tilt between the two groups were compared, only differences to upright tilt between the two groups were observed. The results of this investigation suggest that upright tilt and the Valsalva maneuver might serve as better predictors of autonomic reflexes in hypertensive patients than the grip test.

Autonomic Nervous System↗
PubMed1981

The mechanism for the renal hemodynamic and tubular action of furosemide.

The mechanism for the renal hemodynamic and tubular action of furosemide (F) was investigated in nine anesthetized dogs. F was administered intrarenally at 50 micrograms/ml/min in isotonic saline with and without the addition of indomethacin (I) at 36 micrograms/ml/min and PGE1 at 2 micrograms/ml/min in isotonic saline. F increased the ERPF, RBF, UV, Cosm, CH20, UNaV and UKV from the experimental kidney and UV, Cosm, CH20, UNaV and UKV from the control kidney. It decreased the RVR of the experimental kidney and had no effect on GFR and MAP. I administration alone produced effects opposite to those of F. The addition of F to I reversed the renal hemodynamic effects of I but partly its tubular effects. The addition of PGE1 to I + F infusion further increased the fractional excretion of free water by both kidneys but had not other effects. The results of the present investigation suggest that the renal hemodynamic effects of F ar not mediated through the action of prostaglandins but rather due to a direct vascular effect of the drug. On the other hand, its tubular actions are mediated through prostaglandins.

Animals↗
PubMed1980

Systemic and renal hemodynamic effects of trimazosin: a new vasodilator.

Trimazosin was administered for 2 days in doses-ranging from 50 to 200 mg to 16 patients with essential hypertension. The patients were randomized on the third day and received either the active drug in a single dose of 300 mg or a placebo. Systemic hemodynamic studies in both the supine and 50 degrees upright tilt position, including the Valsalva maneuver and a 1 min sustained handgrip test at 30% maximal voluntary contraction, were performed during control and 0, 1, 2, and 3 hr after drug administration. Renal function studies including plasma renin activity (PRA) were performed during control period and 3 hr after drug administration. Trimazosin reduced arterial pressure and peripheral vascular and renal vascular resistances, increased heart rate, cardiac output, and renal blood flow, and had no effect on glomerular filtration rate or PRA. Placebo had no effect on any of the above-mentioned parameters. The increase in renal blood flow was independent of cardiac output. We conclude that trimazosin lowers arterial pressure through a direct arteriolar dilation and reduction in peripheral vascular resistance. Its direct renal effects would make it a useful agent in the treatment of hypertension associated with renal function impairment.

Adult↗
PubMed1980

Renal functional and organic changes induced by salt and prostaglandin inhibition in spontaneously hypertensive rats.

The prolonged (3 months) effects of high sodium intake and sodium meclofenamate were studied in two groups of male spontaneously hypertensive rats. Group 1 (8 rats) received 1% NaCl in tap water ad libitum and served as control. Group 2 (8 rats) received, besides 1% NaCl in tap water, 50 micrograms/ml of sodium meclofenamate per rat daily. Renal metabolic, hemodynamic and histologic studies were done at the end of the study. The renal functional studies were performed in the unanesthetized, unrestrained state. Group 2 rats developed significantly higher arterial pressures, renal vascular resistance and histologic changes (p less than 0.005), larger left ventricular weights (p less than 0.05) and significantly lower effective renal plasma flow, renal blood flow (p less than 0.005) and glomerular filtration rate (p less than 0.05) than group 1 rats. There were no differences between the two groups of rats with respect to heart rate, hematocrit, right ventricular weight, body weight, fluid intake, urine output, sodium and potassium excretion and serum electrolytes. The results suggest that the combination of high sodium intake and prostaglandin synthesis inhibition exert a greater damaging effect on the arterial pressure and renal function of spontaneously hypertensive rats than salt alone.

Animals↗
PubMed1979

Effects of high salt intake and meclofenamate on arterial pressure and renal function in the spontaneously hypertensive rat.

1. The effects of prolonged high sodium intake (duration 3 months) and meclofenamate were studied in two groups of male spontaneously hypertensive (SH) rats. 2. Group 1 (eight rats) received 1% NaCl in water and served as controls, and group 2 received 1% NaCl in water plus meclofenamate (3.5-4.0 mg daily). 3. Group 2 rats developed higher arterial pressure, renal vascular resistance and left ventricular weight and greater renal histological changes, with lower effective renal plasma flow, renal blood flow and glomerular filtration rate, than group 1. No differences were observed between the two groups in heart rate, body weight, fluid intake, urine volume, UNaV, UKV and right ventricular weight. 4. The results suggest that the combination of high sodium intake and meclofenamate exerts a greater damaging effect on the arterial presssure and renal function of SH rats than salt alone.

Animals↗
PubMed1979

Antihypertensive and renal effects of tienilic acid.

Tienilic acid, a diuretic agent effective at the cortical diluting segment of the distal tubule, has been found to have equivalent antihypertensive action in a dose of 250 mg twice daily to hydrochlorothiazide in a dose of 50 mg twice daily. Tienilic acid reduced arterial pressure without diminishing renal plasma flow or endogenous creatinine clearance; moreover, it did so whilst achieving hypouricaemia through a uricosuric effect. Hypokalaemia was observed but corrected by supplemental potassium. A transient but reversible, slight elevation in serum creatinine concentration and significant hypertriglyceridaemia were also observed. In conclusion, tienilic acid seems to be a novel diuretic, well-suited for the patient with hypertension, particularly if there is coincidental gout or coexisting hyperuricaemia.

Glycolates↗
PubMed1978

Ticrynafen: a novel uricosuric antihypertensive natriuretic agent.

Interest in new diuretics with less side effects has led to the synthesis of ticrynafen, an uricosuric diuretic. This agent was compared with hydrochlorothiazide in a crossover design study involving 12 hypertensive men. Both agents significantly decreased mean arterial pressure from 8% to 18% in eight of the 12 patients. In addition to reducing body weight, these diuretics induced reversible changes in BUN and carbon dioxide content (increased) and plasma concentration of potassium and chloride ions (decreased). The most important change in renal function was a 2.5-fold increase in fractional urate clearance by ticrynafen associated with reduction of serum uric acid by 62%. Thus, ticrynafen is a promising therapeutic agent in hypertension, adding a unique uricosuric effect that should improve patient compliance.

Blood Pressure↗
PubMed1978

Abrupt cessation of clonidine administration: a prospective study.

In 20 patients with mild to moderate hypertension, the effects of abrupt cessation of clonidine therapy on blood pressure, heart rate and catecholamine excretion were evaluated. In a double blind, crossover study, placebo was substituted for clonidine after 3 days of therapy and again after 30 days. The results demonstrated no instances of clinically significant symptoms or overshoot in blood pressure or heart rate. There was an overshoot in norepinephrine excretion that approached the upper limits of normal. Thus, a clinical withdrawal syndrome associated with abrupt cessation of clonidine was not seen in this study of patients without severe hypertension who were given the drug without a diuretic agent.

Adult↗
PubMed1978

Hemodynamic correlates of saralasin-induced arterial pressure changes.

Angiotensin antagonists have proved useful in elucidating the clinical role of the renin-angiotensin system; and their diagnostic and therapeutic efficacy in hypertension has been the subject of many reports but the hemodynamic effects remain unknown. Therefore, saralasin was infused intravenously (1.3 mg/min for 30 min) in 26 sodium-depleted patients with hypertension. Systemic hemodynamic alterations were determined before, during, and after infusion. On the basis of mean arterial pressure (MAP) changes, patients were classified as responders, nonresponders, or pressorresponders (MAP changes greater than or equal to 10 mm Hg). MAP fall in responders was achieved through reduced cardiac output and/or total peripheral resistance, with minimal or absent reflexive heart rate increase. In nonresponders, despite no change in MAP, output fell in parallel with stroke index and left ventricular ejection rate, In pressorresponders, saralasin increased vascular resistance. Thus, in addition to variable effects on vascular receptors, saralasin produced inhibitory cardiac effects either through altered venous return or inhibition of contractility.

Adult↗
PubMed1978

Hemodynamic changes induced by prolonged NaCl and DOCA administration in spontaneously hypertensive rats.

The results of this study demonstrate that the spontaneously hypertensive rat is sensitive to salt excess. The hypertensinogenic effect of salt was mediated through elevation of peripheral vascular resistance. The addition of DOCA aggravated the hypertension, mainly be elevating the cardiac output without appreciably decreasing peripheral vascular resistance. SHR'S EXPOSED TO 1% NaCl consumed more fluids and excreted more sodium and urine than control rats. Those exposed to 1% NaCl and DOCA had higher fluid consumptions and excreted more sodium than the other two groups. These effects of sodium in a neurogenic strain of hypertensive rats suggest a possible interplay between the neurogenic and salt-dependent components in the development and maintenance of hypertension. They also suggest that SHRs, like other hypertensive rat models, are salt sensitive.

Animals↗
PubMed1978

Hemodynamic effects of isometric exercise in normotensive and hypertensive subjects.

Isometric exercise increases arterial pressure and heart rate in normotensive individuals and also in patients with labile and fixed essential hypertension. The hypertensinogenic effect of isometric exercise is mediated through an increase in cardiac output because the peripheral vascular resistance is usually not affected. The cardioaccelerating effects of isometric exercise are mediated through an initial vagal withdrawal and a later stimulation of the sympathetic system. However hypertensive patients with defective sympathetic adjustments are not immune to the hypertensinogenic and cardioaccelerating effects of isometric exercise. Since isometric exercises are performed several times during daily activities, they may result in dangerous elevations in arterial pressure in patients with already increased arterial pressure, and this may eventually lead to cerebrovascular accidents and/or cardiac decompensation. It is therefore recommended that patients with elevated arterial pressure, or persons prone to hypertension, should refrain from such activities.

Blood Pressure↗