Pressor reactivity to norepinephrine and angiotensin in salt-sensitive hypertensive patients

The mechanisms responsible for increased blood pressure in response to a high dietary sodium intake in salt-sensitive patients with essential hypertension are only partially understood. The possibility that increased reactivity to pressor hormones might contribute to hypertension in these patients has not been adequately investigated. We studied 11 salt-sensitive and 15 salt-resistant patients with essential hypertension while they were ingesting a diet with 20 meq/day sodium for 9 days or one with 200 meq/day sodium for 14 days. During the last 4 days of each dietary regimen, they received 30 mg/day of slow-release nifedipine. Blood pressure response to increasing doses of norepinephrine and angiotensin II (Ang II) was studied at the end of each of four phases of the study. Salt-sensitive patients exhibited a greater blood pressure response to norepinephrine than salt-resistant patients, irrespective of the dietary sodium intake and whether we took into account the dose infused or the actual plasma levels of norepinephrine achieved during the infusion. The blood pressure response to Ang II, on the other hand, was greater in salt-sensitive than salt-resistant patients during low but not during high sodium intake. The blood levels of norepinephrine achieved during the infusion of this hormone were lower in salt-sensitive than in salt-resistant patients. These studies indicate that an increased reactivity to the pressor action of norepinephrine might contribute to the maintenance of hypertension in salt-sensitive patients. The increased reactivity appears to be specific for norepinephrine. In fact, we observed increased reactivity to Ang II during low but not during high sodium intake.(ABSTRACT TRUNCATED AT 250 WORDS)

Impaired phagocytosis in chronic renal failure is mediated by secondary hyperparathyroidism

Patients with chronic renal failure (CRF) display impaired phagocytosis by the polymorphonuclear leucocytes (PMNL), and these cells have elevated basal levels of cytosolic calcium ([Ca2+]i) and reduced ATP content. It has been suggested that these changes in PMNL metabolism and function are mediated by the state of secondary hyperparathyroidism of CRF. To examine the role of excess PTH in these derangements of PMNL, we studied [Ca2+]i, ATP and phagocytic ability of PMNL in five groups of rats including: CRF, CRF normocalcemic parathyroidectomized (CRF-PTX), CRF and normal animals treated with verapamil (CRF-V), and normal-V, respectively. The level of [Ca2+]i in the PMNL of CRF rats (149 +/- 2.7 nM) was significantly (P less than 0.01) higher and the ATP content (4.2 +/- 0.17 nmol/5 x 10(6) PMNL) significantly lower (P less than 0.01) than in normal (108 +/- 2.4 nM; 9.5 +/- 0.15 nmol/5 x 10(6) PMNL), CRF-PTX (103 +/- 2.9 nM; 9.2 +/- 0.19 nmol/5 x 10(6) PMNL), CRF-V (107 +/- 2.2 nM; 9.0 +/- 0.2 nmol/5 x 10(6) PMNL) and normal-V (106 +/- 1.8 nM; 9.2 +/- 0.2 nmol/5 x 10(6) PMNL), despite sustained elevation in blood PTH in the CRF-V group. Phagocytosis was significantly (P less than 0.01) impaired in CRF animals (5.6 +/- 0.25 micrograms oil/10(7) PMNL/min) but was normal in CRF-PTX (9.3 +/- 0.21 micrograms oil/10(7) PMNL/min) and CRF-V (9.5 +/- 0.22 micrograms oil/10(7) PMNL/min) rats. The values of phagocytosis in normal and normal-V rats were 9.6 +/- 44 and 9.6 +/- 0.18 micrograms oil/10(7) PMNL/min, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

On the mechanisms of impaired phagocytosis in phosphate depletion

Phosphate depletion (PD) impairs the phagocytic ability of polymorphonuclear leukocytes (PMNL). This derangement has been attributed to the low ATP content of PMNL in PD. The mechanisms responsible for the low ATP content are not well defined. Phosphorus deficiency, per se, and/or other cellular metabolic consequences of PD such as a rise in cytosolic calcium ([Ca2+]i) could be responsible. Indeed, PD is associated with a rise in [Ca2+]i in other cells, and such an event may inhibit mitochondrial ATP production. It is also not evident whether the impaired phagocytosis in PD is due to low ATP content and/or a rise in the [Ca2+]i of PMNL. The study presented here examined levels of [Ca2+]i, ATP content, and the phagocytic ability of PMNL from PD and pair-weighed (PW) rats and evaluated the potential beneficial effect of treatment with verapamil (V), which may prevent a rise in [Ca2+]i and the consequent effects on ATP content and the phagocytosis of PMNL. The resting levels of [Ca2+]i of PMNL from PD rats (148 +/- 3.9 nM) were significantly (P less than 0.01) higher, and the ATP contents (4.8 +/- 0.2 nmol/5 x 10(6) PMNL) were significantly (P less than 0.01) lower than in PW (111 +/- 2.8 nM and 9.3 +/- 0.3 nmol/5 x 10(6) PMNL), PW-V (114 +/- 2.2 nM and 9.3 +/- 0.28 nmol/5 x 10(6) PMNL), and PD-V (112 +/- 1.8 nM and 6.6 +/- 0.19 nmol/5 x 10(6) PMNL) animals. Despite the normal [Ca2+]i in the PMNL of PD-V rats, their ATP contents were still significantly (P less than 0.01) lower than those of PW or PW-V rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Bilateral renal cortical necrosis in two patients with Neisseria meningitidis sepsis

Two patients who developed bilateral renal cortical necrosis as a consequence of Neisseria meningitidis infections are described: 1 patient had meningococcemia and the other had meningococcal meningitis. Both patients developed a Shwartzman-like reaction, disseminated intravascular coagulation and irreversible renal failure. Renal biopsy showed sclerosis of the majority of glomeruli; some glomeruli showed capillary congestion, thrombosis and an increased number of neutrophils; the intralobular arterioles showed thrombotic occlusions.