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Query: UMLS:C0085580 (essential hypertension)
 14,686 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Circadian blood pressure rhythm exhibits a typical biphasic pattern in normotensives and in patients with primary hypertension. It is, however, disturbed in patients with secondary hypertension. There is ample evidence suggesting a major role for the sympatho-adrenergic system in regulating this rhythm. In order to investigate this relationship more accurately, the sympatho-adrenergic activity was studied in 20 patients with normal blood pressure, 20 patients with primary hypertension, and in patients with several diseases characterized by an abnormal catecholamine secretion, e.g. two pheochromocytomas, one adrenomedullary hyperplasia, and two Shy-Drager syndromes. Catecholamine concentrations were measured in plasma and urine, cAMP concentrations in plasma or in lymphocytes, and beta-adrenoceptor density and affinity on lymphocytes, and 24-h blood pressure monitoring was conducted. The data shows synchronicity of the circadian blood pressure rhythm and the sympatho-adrenergic activity both in normotensives and in patients with primary hypertension with normal circadian rhythm, and in abnormal catecholamine secretion with an abnormal circadian blood pressure curve. It is concluded that sympatho-adrenergic mechanisms play an important role in controlling and regulating circadian blood pressure.
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PMID:[Synchronized circadian blood pressure rhythm and sympatho-adrenergic activity]. 132 91

Plasma humoral factors which modulate the transmembrane distribution of sodium and calcium have been identified in hypertensive patients and have been hypothesized to be involved in the etiology of essential hypertension. In cross-incubation experiments, we have found that plasma of hypertensive subjects elevated basal and stimulated intraplatelet calcium levels, while plasma of normal subjects has an opposite effect on platelets from hypertensives. Basal intraplatelet calcium in normal platelets was 108 +/- 5 nmol/L and rose to 142 +/- 3 nmol/L (P less than .001) after incubation in plasma from hypertensive patients. Platelets from hypertensive patients had basal calcium levels of 182 +/- 11 nmol/L which fell to 127 +/- 11 nmol/L (P less than .01) after incubation in normal plasma. Hypertensive plasma potentiated the rise in intraplatelet calcium in response to ADP and PAF. Hypertensive patients treated experimentally with plasmapheresis exhibited a disappearance of the plasma factor responsible for elevating intraplatelet calcium. These results indicate the presence of a plasma humoral factor in hypertensives which elevates intraplatelet calcium and sensitizes platelets to agonist stimuli.
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PMID:Humoral factor, intraplatelet calcium, and hypertension. 163 35

The effects of dietary salt on circulating levels of 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine (C16 PAF) in patients with essential hypertension were studied by gas chromatography/mass spectrometry with negative ion chemical ionization. Circulating levels of C16 PAF in patients with essential hypertension (18.1 +/- 5.3 pg/ml, n = 16) were not changed compared with those in normotensive subjects (17.2 +/- 7.2 pg/ml, n = 14). Although changes in circulating levels of C16 PAF were small with changes in dietary salt, net changes in circulating C16 PAF levels significantly and positively correlated with net changes in mean arterial blood pressure (r = 0.47, P less than 0.05). Changes in C16 PAF levels also correlated with changes in creatinine clearance (r = 0.55, P less than 0.05). However, changes in C16 PAF levels did not correlate with changes in plasma sodium concentration, plasma chloride concentration and plasma volume. These results indicate that C16 PAF plays an antihypertensive role and this may be reflected as small changes in circulating levels of C16 PAF.
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PMID:Dietary salt, blood pressure and circulating levels of 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine in patients with essential hypertension. 251 2

It is reported that plasma platelet-activating-factor-acetylhydrolase (PAF-AH) is elevated in patients with essential hypertension. In this study, plasma PAF-AH activity was measured during pregnancy and after delivery to examine the relationship between plasma PAF-AH activity and the development of transient hypertension (TH) during pregnancy. Moreover, in order to examine the involvement of endothelial injury in TH, the plasma level of nitric oxide metabolite (NOx; NO2+NO3) was measured. The plasma PAF-AH activity in 51 pregnant women was consecutively measured in the 1st, 2nd and 3rd trimesters of gestation, and after delivery. Forty-one cases were normal pregnancies and 10 cases were complicated by TH later during pregnancy. The PAF-AH activity in the normal pregnancy group decreased in the 2nd trimester of gestation compared with the 1st trimester, but was elevated in the TH group. The incidence of elevation of PAF-AH in the TH group was significantly (7/10; 70.0%; P<0.01, Chi-squared test) higher than in the normal pregnancy group (9/41; 22.0%). The plasma NOx levels in the 2nd trimester were higher than those in the 1st trimester in both the normotensive and TH group (P<0.05 for both comparisons). The 51 patients were classified into two groups according to the change in the PAF-AH in the 2nd trimester: group A consisted of 35 patients whose PAF-AH activity did not increase, and group B consisted of 16 patients whose PAF-AH activity increased. The incidence of development of TH during later pregnancy in group B was significantly (7/16; 43.8%; P<0.01, Chi-squared test) higher than in group A (3/35; 8.6%). Hypertension developed after 36 weeks' gestation in all patients in the TH group. The results of the present study suggest that changes in PAF metabolism may relate to regulation of blood pressure in pregnant women whose pregnancy is complicated with TH, whereas NO metabolism does not differ between women with TH and those having a normal pregnancy.
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PMID:Activity of platelet-activating-factor-acetylhydrolase and the nitric oxide metabolite level in the plasma of pregnant women who develop transient hypertension during later pregnancy. 1073 50

Ambulatory blood pressure monitoring(ABPM) permits 24-hour measurement of blood pressure(BP) without restricting the subject's activities. The tilting test is used to evaluate BP variability and autonomic nervous responses, especially baroreceptor reflex sensitivity(BRS) during changes of body position. The change of BP and BRS are common to both ABPM and the tilting test. In this instance, BRS is expressed as the ratio between heart rate(HR) variation and systolic BP variation(delta RR/delta SBP). The results were the same as those produced by all other tests including sequential method, squatting test, the neck chamber method, and tilting test. Therefore, we investigated the correlation between BRS and BP changes monitored mainly by means of ABPM. Twenty-four-hour BP variation(SD) manifest both short-term variability(SDh), and long-term variability extending over 24 hours(SD24) (SD2 = SDh2 + SD24(2). In the former case(SDh), atherosclerosis and lowered BRS participate, and in the latter case(SD24), activation of the sympathetic nervous system(SNA) participates strongly. Each BP value during 24 hours(Pi: i = 1, 2, ... 10(5)) is expressed by the product(Pi = phi i x P0) of the ratio of variability(phi i) and sleep-time base BP(P0) values. The phi i is expressed by HR variation and two elements: the cardiovascular response element and the BRS element. In mild cases of essential hypertension, the correlation between Pi and HR variation is high. In severe cases of essential hypertension and in cases of Shy-Drager syndrome, short-term phi i caused by BRS decrease is large, and the correlation between phi i and HR variation during 24 hours drops. Although measuring short-time variability indirectly with ABPM is impossible, BRS can be evaluated on the basis of the product(BI) of diastolic BP(Pd) and pulse interval(RR). The multi-biomedical recorder(TM2425, A&D, Co.) permits 24-hour monitoring of body position and daily activities(acceleration), simultaneous with evaluation of BI, which is related to autonomic nervous activity and BRS. Its employment is, therefore, considered clinically useful.
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PMID:[Utility and limitations of ambulatory blood pressure monitoring and tilting test: evaluation of baroreceptor reflex sensitivity]. 1083 64

Disabling orthostatic hypotension dominates the clinical picture of autonomic failure. Nonetheless, severe supine hypertension is observed in about 50% of patients. In patients with multiple system atrophy (Shy-Drager syndrome), supine hypertension is explained by residual sympathetic tone because it can be eliminated with the ganglionic blocker trimethaphan. The cause of hypertension in patients with pure autonomic failure is not known and its understanding may be relevant to essential hypertension. Supine hypertension complicates the treatment of these patients but can be managed by overnight administration of antihypertensive medications.
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PMID:Hypertension in orthostatic hypotension and autonomic dysfunction. 1211 2