Sodium ionophore converts growth manner of vascular smooth muscle cells from spontaneously hypertensive rats.

OBJECTIVES: Vasoconstrictor peptides such as endothelin (ET) cause hypertrophy of vascular smooth muscle cells (VSMC) in Wistar Kyoto rats (WKY) and hyperplasia in spontaneously hypertensive rats (SHR). They also induce an increase in Na+ concentration ([Na+]i) and activate protein kinase C (PKC) independently. Therefore, we tested the hypothesis that the increase in [Na+]i may be involved in the conversion of growth manner under activated PKC in SHR VSMC. METHODS AND RESULTS: 10(-7) M phorbol ester (TPA) increased the diameter and protein content of VSMC from both strains under 18% serum conditions. Further addition of 10(-6) M gramicidin (Na+ ionophore) converted TPA-induced hypertrophy to hyperplasia, which was due to the quick transition from S to G2/M phase, only in SHR VSMC. Western blot analysis showed that serum- and TPA-induced tyrosine phosphorylation of mitogen-activated protein (MAP) kinase was potentiated by 10(-6) M gramicidin in SHR. [Na+]i, which was measured by sodium-binding benzofuran isophthalate (SBFI), was increased about 35 mM by 10(-6) M gramicidin in both strains, but TPA did not affect basal [Na+]i and the gramicidin-induced increase in [Na+]i. CONCLUSIONS: We conclude that sodium ionophore may convert hypertrophy to hyperplasia synergistically with activated PKC in SHR VSMC, possibly by MAP kinase phosphorylation.

Significance of sympathetic nervous system in sodium-induced nocturnal hypertension.

OBJECTIVE: The purpose of this study was to investigate the effects of salt loading on circadian patterns of blood pressure (BP) and sympathetic nervous activity. SUBJECTS AND METHODS: Seventy-six patients with essential hypertension were hospitalized and placed on a low-salt diet (2 g/day) for 7 days followed by a high-salt diet (20-23 g/day) for another 7 days. On the last day of each salt diet, 24 h ambulatory BP, plasma noradrenaline concentrations, urinary noradrenaline excretion, plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were measured. Patients whose average mean BP was increased by more than 10% by salt loading were assigned to the salt-sensitive (SS) group (n = 44); the remaining patients, whose mean BP was increased by less than 10%, were assigned to the non-salt-sensitive (NSS) group (n = 32). RESULTS: Salt loading converted the circadian pattern of BP from dippers, whose mean BP during the night-time was decreased by more than 10% from the daytime BP, to non-dippers in the SS group but not in the NSS group. A nocturnal decrease in plasma noradrenaline concentration was unaffected after salt loading in the NSS group but dampened in the SS group. The night-time/daytime ratio of urinary noradrenaline excretion, which was increased after salt loading in the SS group only, was greater in the SS group than in the NSS group under the high-salt diet. The salt-induced suppression rate of PRA and PAC was similar between the SS and NSS groups. CONCLUSION: BP fails to fall during the night under the high-salt diet in patients with the SS type of essential hypertension. This may be related to the lack of nocturnal decrease in sympathetic nervous activity.

Salt-induced exacerbation of morning surge in blood pressure in patients with essential hypertension.

The morning surge in blood pressure (BP) is related to the morning occurrence of lethal cardiovascular events. We tested the hypothesis that salt intake may be associated with the morning surge in BP in essential hypertension. Seventy-six patients were admitted and placed on a low salt diet (2 g/day) for 7 days followed by a high salt diet (20-23 g/day) for another 7 days. At the end of each salt diet, 24-h ambulatory BP and heart rate monitorings and head-up tilt (HUT) test were performed. Patients whose average mean BP (MBP) was increased by more than 10% by salt loading were assigned to the salt-sensitive (SS) group (n = 37); the remaining patients, whose MBP was increased by less than 10%, were assigned to the non-salt-sensitive (NSS) group (n = 39). The increase in ambulatory MBP during 6.30-8.00 am above the baseline (2.00-4.00 am) was significantly enhanced by salt loading in the NSS group (P < 0.05), but not in the SS group. The coefficient of variation of 24-h MBP and heart rate was increased by salt loading only in the NSS group. The significant elevation of plasma noradrenaline concentration after awakening, which was noted during the low salt diet period, was unchanged during the high salt diet period in the NSS group, but abolished in the SS group. Salt loading enhanced HUT-induced decrease in systolic BP without affecting the heart rate response only in the NSS group. We conclude that the morning surge in BP is enhanced by salt loading in the NSS type of essential hyper- tension, presumably by the excessive activation of the sympathetic nervous system. Journal of Human Hypertension (2000) 14, 57-64.

Postoperative hyperperfusion syndrome in elderly patients with chronic subdural hematoma.

BACKGROUND: Temporary acute agitated delirium is a frequent complication after surgery for chronic subdural hematoma (CSH) in elderly patients. To clarify the pathogenic mechanism underlying this complication, we measured cerebral blood flow before and after surgery in elderly patients with CSHs. METHODS: Twenty-seven patients aged 75 years or older with unilateral CSH underwent treatment involving a single burr hole craniostomy with continuous catheter drainage. Cerebral blood flow was measured using single photon emission computed tomography 1 day before surgery, and at 1 hour and 24 hours after surgery. Acute agitated delirium was diagnosed by the characteristic behavioral abnormality. RESULTS: SPECT imaging 1 hour after surgery demonstrated hyperperfusion in the cerebral cortex beneath the CSH in 14 patients (51.9%). Of these 14 patients, five showed acute agitated delirium a few hours after surgery that persisted for 10 to 12 hours. A hematoma was detected in the right hemisphere in all five patients. Hyperperfusion was significantly more intense in patients with acute agitated delirium both 1 hour and 24 hours after surgery than in patients (n = 9) without acute agitated delirium. Moreover, mean arterial blood pressure during the first postoperative hour was significantly higher in patients with acute agitated delirium. CONCLUSION: In elderly patients with CSH, intense and prolonged hyperperfusion after surgery induces temporary acute agitated delirium. This postoperative hyperperfusion syndrome is exacerbated by hypertension.

[A case of intrasellar pure germinoma].

A 19-year-old male presented with progressive loss of vision and diabetes insipidus due to an intra- and suprasellar tumor. Transsphenoidal exploration revealed a pure germinoma. Seven days after the operation, bleeding from the residual tumor caused headache and right occulomotor palsy. The residual tumor and hematoma were removed using pterional approach. The residual tumor disappeared after postoperative irradiation. After 5 months of radiation, multiple lesions due to dissemination of the germinoma were discovered in the suprasellar region. Adjuvant chemotherapy and whole supratentorial irradiation were performed. All lesions regressed completely. Mid-sagittal magnetic resonance image was useful in our patient for differential diagnosis between intrasellar germinoma and pituitary adenoma. Before initiating an operation for intrasellar germinoma, awareness is needed for the fact of postoperative bleeding. We notice that transsphenoidal surgery should be selected for treatment of postoperative bleeding from intrasellar germinoma.

[Effect of aging on sensitivity of blood pressure to salt].

We investigated the correlation between aging and sensitivity of blood pressure to salt. 88 non-treated essential hypertensives were divided into four groups: less than 40 years old (n = 20), 40-49 years old (n = 20), 50-59 years old (n = 39), and greater than 60 years old (n = 11). Changes of blood pressure, plasma renin activity (PRA), plasma aldosterone concentration (PAC), plasma norepinephrine (PNE), and plasma epinephrine (PE) due to salt load were compared among four groups. Salt sensitivity of blood pressure was increased with aging, and there was a positive correlation between them (r = 0.30, p < 0.01). Decrement of PRA due to salt load was decreased with aging, and there was a negative correlation between them (r = -0.35, p < 0.05). PCA and PNE were suppressed by salt load, and the decrement degrees did not change with age. PE did not change by salt load. We conclude that salt sensitivity is increased with age in essential hypertensives, and renin-angiotensin system might be involved in it.