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Query: UMLS:C0031511 (pheochromocytoma)
 14,622 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Authors assessed correlation between venous blood catecholamines and prostaglandins concentrations before and after inhibition of sympathetic activity by clonidine in patients with primary hypertension or pheochromocytoma. 30 patients with essential uncomplicated hypertension and 11 with pheochromocytoma underwent the study. The control group consisted of 6 healthy volunteers. Serum norepinephrine (NA), epinephrine (A), prostaglandins: PGE2 PGF2 alpha and prostacyclin metabolite -6-keto-PGF1 alpha were determined before and 3 hours after oral administration of 0.3 mg clonidine. Negative correlation was stated between basic serum norepinephrine and 6-keto-PGF1 alpha concentrations in patients with pheochromocytoma, which could indicate prostacyclin metabolism disorders during persistent hypercatecholaminemia . There was no correlation between catecholamines and prostaglandins during the inhibition of sympathetic activity in patients with pheochromocytoma as well as essential hypertension. The positive correlation was observed between changes in serum NA and PGF2 alpha levels in patients with borderline hypertension. Thus, one may suppose, that correlation between na excretion and vasoconstrictive PGF2 proved in acute experiments, becomes evident within the early stage of hypertension also during sympathetic activity inhibition.
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PMID:[Correlations between catecholamines and prostaglandins in patients with primary arterial hypertension and pheochromocytoma in basic conditions and after administration of clonidine]. 208 2

Clonidine, an agonist of central alpha-2-adrenergic receptors, reduced the peripheral sympathetic activity. With regard to the mutual pathophysiological relationship of blood pressure regulating mechanisms, the authors wanted to find out whether after clonidine administration, in addition to the known suppression of catecholamine levels (CA), also changes in the concentration of other pressor and depressor humoral substances will occur. They investigated therefore in 15 patients with essential hypertension (EH) and in three patients with pheochromocytoma the urinary excretion of free noradrenaline (NA), adrenaline (A) and dopamine (DA), the plasma renin activity (PRA), the aldosterone concentration (PAC) and atrial natriuretic factor (ANF) in plasma, using radioimmunoanalysis, always before and 24 hours after clonidine administration (Haemiton retardR) by the oral route. Its administration led in patients with EH to a decline of NA and DA. On the other hand, in pheochromocytoma their urinary excretion did not change in an unequivocal way, and when it declined, never normal NA and DA levels were reached. A excretion remained unaltered in both groups of patients. The drop of PRA after clonidine as a result of the drop of peripheral adrenergic activity was not associated with an expected parallel drop of PAC but by its rise. This effect can be explained by a reduction of the tonic inhibition of PAC output when the DA level declines. The rise of ANF after clonidine administration will be the subject of subsequent investigations. It cannot be ruled out that this effect is due to the direct action of clonidine on alpha receptors in the heart.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[The effect of clonidine on humoral factors in patients with arterial hypertension]. 214 Feb 96

This paper updates the current view on clinical significance of systolic time intervals (STI) in estimating the cardiac changes associated with hypertension. The following three intervals were measured as STI: (1) electromechanical systole (QS2 interval); (2) left ventricular ejection time (LVET) and (3) pre-ejection period (PEP). Firstly, the influences of changes in heart rate, preload, afterload and myocardial contractility upon each interval were reviewed; secondly, clinical applications of STI in various types of hypertension such as essential hypertension, hypertension with angina pectoris and pheochromocytoma were studied. In patients with essential hypertension, there was a good positive correlation between PEP and left ventricular mass, and a shortening of LVET was observed only at the decompensated stage. The changes in STI in angina pectoris with or without hypertension were similar and were different from those in essential hypertensives. STI in patients with pheochromocytoma were characterized by a marked shortening of QS2 and LVET with normal PEP. These findings indicate the usefulness of STI in detecting cardiac changes in various types of hypertension.
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PMID:Clinical significance of systolic time intervals in hypertensive patients. 215 Nov 86

Platelet and plasma catecholamine concentrations were determined in 17 patients with surgically proven pheochromocytoma (mean age 42.3 years); in 31 patients with borderline hypertension (mean age 35.3 years) and in 9 healthy controls (mean age 39.3 years). Both platelet norepinephrine and epinephrine were significantly increased in patients with pheochromocytoma when compared with hypertensive and control groups (P less than .001). No correlation between platelet and plasma catecholamines was detected in all studied groups. The diagnostic accuracy of platelet catecholamine in pheochromocytoma is limited since increased platelet norepinephrine was found in 35.5% and increased platelet epinephrine was found in 19.4% of patients with essential hypertension.
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PMID:Platelet norepinephrine and epinephrine concentration in patients with pheochromocytoma. 222 53

We examined the hemodynamic features of 24 untreated patients with surgically proven pheochromocytoma during steady-state periods and compared them with 24 untreated essential hypertensive patients individually matched for sex, age, body surface area, and arterial blood pressure. We found that, despite having 10-fold higher levels of circulating catecholamines, pheochromocytoma patients have hemodynamic characteristics similar to patients with essential hypertension and that, in individual patients, the ratio of circulating norepinephrine to epinephrine had no relation to the hemodynamic profile. In both groups, increased total peripheral resistance is primarily responsible for maintenance of hypertension. These results suggest that, unlike the acute administration of catecholamines, long-term exposure to high levels of circulating catecholamines does not produce hemodynamic responses characteristic of this group of compounds. This might be due in part to desensitization of the cardiovascular system to catecholamines and might explain the clinical observation that some patients can be completely asymptomatic despite harboring an actively catecholamine-secreting pheochromocytoma.
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PMID:A reevaluation of the hemodynamics of pheochromocytoma. 229 68

The phasic structure of heart activity was explored in 50 patients suffering from symptomatic arterial hypertensions before and after the operative treatment with the aid of impulse Doppler echocardiography. Of these, 28 patients had renovascular hypertension (RVH), 16 primary aldosteronism (PA), and 6 pheochromocytoma of the adrenals. The data obtained were compared with the polycardiographic readings in patients with essential hypertension (EH). As in the case of EH, the period of left ventricular tension, the phase of asynchronous and isometric contraction, and the phase of isometric relaxation became significantly longer in patients with RVH and PA. In the postoperative period, some phases of heart activity return to normal whereas other phases remained altered throughout the entire observation period, which may be due to the disease standing and irreversibility of myocardial alterations. Therefore, Doppler echocardiography is a sufficiently accurate method of estimating phasic activity of the left ventricle, allowing computation of the period of cardiac cycle phases even in the presence of only one lead of the ECG mounted into an ultrasonic outfit.
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PMID:[Potential of pulsed Doppler echocardiography in assessing the phasic activity of the left ventricle in patients with symptomatic arterial hypertension]. 239 60

Alpha-adrenergic activity mediated by the autonomic nervous system, consisting of the release of norepinephrine and its engagement by the alpha receptors, is a recognized pathway for arteriolar vasoconstriction. The pathway is well traveled in acute reactions to emotion and stress, but this complicity in chronic hypertension other than pheochromocytoma has been more difficult to show. Among the reasons for the difficulty is the failure to develop an animal model of hypertension mediated through the nervous system. Another reason is the uncertainty as to whether or not measurements of plasma norepinephrine really reflect what is happening at the synapse. Nevertheless, treating essential hypertension with alpha blockade has always been attractive to investigators. The potential has remained tantalizing by the occasional clinical success, at least in depressor terms, of the early ganglionic blocking agents. However, until quite recently that potential has been held out of reach by the unpredictability of these drugs, the undiscriminating nature of their gross blockade of the autonomic nervous system, and their baggage of disturbing side effects. Now it can be reported that a succession of alpha-adrenergic blocking agents, with increasing presynaptic specificity, has assembled indirect but persuasive evidence of alpha-adrenergic participation in definable forms of hypertension. They include guanethidine, phentolamine, phenoxybenzamine, prazosin, and now indoramin. In mapping autonomic pressor activity as indicated by the response to blockade, these pharmacologic probes have made abundantly clear a central fact that we always knew but tended sometimes to forget: namely, that hypertension is a heterogeneous phenomenon.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Potential of alpha blockade in treating human hypertension: a role for indoramin. 242 95

To investigate the possible release of beta-endorphins (beta EN) from tumors and to investigate their possible involvement in the hypotensive mechanism of clonidine (CLO) in pheochromocytoma (PHEO), as compared with essential hypertension (EH), we studied 12 patients with PHEO, 17 patients with uncomplicated stable EH (SEH), nine patients with borderline EH (BEH), and seven healthy volunteers (N). All subjects were hospitalized and excreted normal amounts of sodium. Mean blood pressure (MAP) and plasma beta EN, norepinephrine (NE), epinephrine (E), and dopamine (DA) were measured before and 180 min after an oral dose of 0.3 mg CLO. Following CLO, a significant (p less than 0.01) decrease in MAP was present in all groups. Plasma NE and E decreased (p less than 0.02 to p less than 0.01) in N, BEH, and SEH, but not in PHEO. DA did not change in any group. Pretreatment beta EN did not differ significantly between the groups, and following CLO it did not change in N or PHEO, while it increased significantly in BEH (p less than 0.01) and in SEH (p less than 0.02). Absolute changes in MAP correlated with those of beta EN only in the SEH group. Changes in NE or E did not correlate with changes in MAP in either group. Likewise, changes in NE or E were not correlated with those of beta EN, in N or EH, but a correlation between resting plasma E and resting beta EN concentrations was demonstrated in PHEO. These results support a role of beta EN in the hypotensive action of CLO in EH, but not in N or PHEO.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Plasma beta-endorphins and catecholamines before and after clonidine in essential hypertension and pheochromocytoma. 245 62

Non invasive 24 hours ambulatory blood pressure monitoring was performed in 81 patients with secondary hypertension (renoparenchymatous nephropathy n = 15, diabetic nephropathy n = 10, Conn's disease n = 4, renal artery stenosis n = 15, pheochromocytoma n = 2, hemodialysis patients n = 15 and patients after kidney transplantation n = 20). The results were compared to 201 patients with essential hypertension. The results showed that 98.5% of patients with essential hypertension have a nightly decline in blood pressure of at least 15 mmHg (systolic + diastolic), whereas 69% of patients with secondary hypertension showed either an attenuated circadian rhythm or no circadian rhythm. Patients with pheochromocytoma who had a night time increase in blood pressure demonstrated the greatest difference to the essential hypertension collective followed by patients with diabetic nephropathy, Conn's disease and the group of patients after kidney transplantation. After successful treatment of the condition leading to hypertension circadian periodicity returned in some patients. In summary these results suggest that the absence of a night time decline in blood pressure during 24-hour-ambulatory monitoring is an indication of secondary hypertension.
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PMID:[Absence of nocturnal decrease in blood pressure in 24-hour blood pressure monitoring: an indication of secondary hypertension]. 266 27

The mosaic of essential hypertension seems to be gaining new tiles at an accelerating rate. Of the many pathophysiological factors and markers for the factors that can be considered as possible elements of a profiling algorithm, there are relatively few with solid data to support their use. Use of plasma renin activity for prospective profiling does not appear to be valid for individual patients. It remains useful for diagnosis of renal artery stenosis and primary aldosteronism. The black race does have some well-documented pathophysiological differences from the white race regarding hypertension, and there are some useful data bits for selecting specific therapy. The elderly, obese patients, and young patients with hyperdynamic circulation appear to have enough group characteristics to enable selection of drugs more targeted to their needs. Anxious patients who often display symptoms that mimic pheochromocytoma symptoms comprise a unique group. One of the largest groups is patients with hypertension plus one or more concomitant diseases. Finally, drug selection decisions must also consider the effect of drugs on serum lipoproteins, left ventricular hypertrophy and vascular compliance, sexual function and other quality of life issues, and cost.
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PMID:Newer principles of patient profiling for antihypertensive therapy. 268 80


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