Characterization of Potassium-Induced Natriuresis in Hypertensive Postmenopausal Women During Both Low and High Sodium Intake.

BACKGROUND: Potassium-induced natriuresis may contribute to the beneficial effects of potassium on blood pressure but has not been well-characterized in human postmenopausal hypertension. We determined the time course and magnitude of potassium-induced natriuresis and kaliuresis compared with hydrochlorothiazide in 19 hypertensive Hispanic postmenopausal women. We also determined the modulating effects of sodium intake, sodium-sensitivity, and activity of the thiazide-sensitive NCC (sodium-chloride cotransporter). METHODS: Sixteen-day inpatient confinement: 8 days low sodium followed by 8 days high sodium intake. During both periods, we determined sodium and potassium excretion following 35 mmol oral KCl versus 50 mg hydrochlorothiazide. We determined sodium-sensitivity as change in 24-hour systolic pressure from low to high sodium. We determined NCC activity by standard thiazide-sensitivity test. RESULTS: Steady-state sodium intake was the key determinant of potassium-induced natriuresis. During low sodium intake, sodium excretion was low and did not increase following 35 mmol KCl indicating continued sodium conservation. Conversely, during high sodium intake, sodium excretion increased sharply following 35 mmol KCl to ≈37% of that produced by hydrochlorothiazide. Under both low and high sodium intake, 35 mmol potassium was mostly excreted within 5 hours, accompanied by a sodium load reflecting the steady-state sodium intake, consistent with independent regulation of sodium/potassium excretion in the human distal nephron. CONCLUSIONS: Potassium-induced natriuresis was not greater in sodium-sensitive versus sodium-resistant hypertensives or hypertensives with higher versus lower basal NCC activity. We studied an acute KCl challenge. It remains to further characterize potassium-induced natriuresis during chronic potassium increase and when potassium is administered a complex potassium-containing meal.

Thiazide-Sensitive NCC (Sodium-Chloride Cotransporter) in Human Metabolic Syndrome: Sodium Sensitivity and Potassium-Induced Natriuresis.

The thiazide-sensitive sodium-chloride cotransporter (NCC;SLC12A3) is central to sodium and blood pressure regulation. Metabolic syndrome induces NCC upregulation generating sodium-sensitive hypertension in experimental animal models. We tested the role of NCC in sodium sensitivity in hypertensive humans with metabolic syndrome. Conversely, oral potassium induces NCC downregulation producing potassium-induced natriuresis. We determined the time course and magnitude of potassium-induced natriuresis compared with the natriuresis following hydrochlorothiazide (HCTZ) as a reference standard. We studied 19 obese hypertensive humans with metabolic syndrome during 13-day inpatient confinement. We determined sodium sensitivity by change in 24-hour mean systolic pressure by automated monitor from days 5 (low sodium) to 10 (high sodium). We determined NCC activity by standard 50 mg HCTZ sensitivity test (day 11). We determined potassium-induced natriuresis following 35 mmol KCl (day 13). We determined (1) whether NCC activity was greater in sodium-sensitive versus sodium-resistant participants and correlated with sodium sensitivity and (2) time course and magnitude of potassium-induced natriuresis following 35 mmol KCl directly compared with 50 mg HCTZ. NCC activity was not greater in sodium-sensitive versus sodium-resistant humans and did not correlate with sodium sensitivity. Thirty-five-millimoles KCl produced a rapid natriuresis approximately half that of 50 mg HCTZ with a greater kaliuresis. Our investigation tested a key hypothesis regarding NCC activity in human hypertension and characterized potassium-induced natriuresis following 35 mmol KCl compared with 50 mg HCTZ. In obese hypertensive adults with metabolic syndrome ingesting a high-sodium diet, 35 mmol KCl had a net natriuretic effect approximately half that of 50 mg HCTZ.

Outcomes of minority patients with very severe hypertension (>220/>120 mmHg).

OBJECTIVES: Acute severe hypertension is a common problem among inner-city ethnic minority populations. Nevertheless, the effects of currently employed treatment regimens on blood pressure have not been determined in a clinical practice setting. We determined the SBP responses to acute antihypertensive drug protocols and the 2-year natural history of patients presenting with severe hypertension. METHODS: Retrospective cohort investigation in consecutive patients with SBP at least 220 mmHg and/or DBP at least 120 mmHg during 3-month enrollment in 2014 with 2-year follow-up. Primary outcomes were SBP versus time for the first 5 h of emergency treatment and 2-year follow-up including repeat visits, target organ events, and hospitalizations. RESULTS: One hundred and fifty-six unique patients met criteria with 69% Black; 34% Hispanic; 56% had previous visits for severe hypertension; 31% had preexisting target injury. Acute management: Acute antihypertensive regimens resulted in grossly unpredictable and often exaggerated effects on SBP. Treatment acutely reduced SBP to less than 140 mmHg in 30 of 159 patients. Clonidine reduced SBP to less than 140 mmHg in 19/61. Two-year follow-up: We observed 389 repeat visits for severe hypertension, 99 new target events, and 76 hospitalizations accounting for 620 hospital days. CONCLUSION: Acute treatment of severe hypertension produced unpredictable and potentially dangerous responses in SBP. Two-year follow-up demonstrated extraordinary rates of recurrent visits, target organ events, and hospitalizations. Our findings indicate a need to develop effective management strategies to lower blood pressure safely and to prevent long-term consequences. Our findings may apply to other hospitals caring for ethnic minority populations.

Prehypertension is real and can be associated with target organ damage.

Prehypertension (systolic blood pressure 120-139 or diastolic blood pressure 80-89 mm Hg) confers a risk of progression to hypertension, impairment of cognitive function, increased left ventricular mass, risk of end-stage renal disease, and an association with arteriosclerosis. Recent studies provide data that could support the rationale for treating prehypertensives subjects with antihypertensive medications in addition to lifestyle modification, especially if they have concomitant cardiovascular risk factors.

Hypertension in the frail elderly.

Extant data indicate that treating to lower systolic pressure confers significant advantage to younger people in general good health and to relatively healthy octogenarians. Few data exist to guide practitioners on the treatment of frail elderly hypertensives. Chronological age alone does not suffice to make useful judgments regarding therapy. The definition of frailty remains controversial. One method, use of a simple questionnaire or a test of walking speed is practical but not universally accepted. Frail subjects, while at higher risk for cardiovascular complications, seem to benefit less or not at all from antihypertensive drug treatment. Clinicians should treat robust older patients as they would younger patients because the benefits far outweigh the low risk of adverse effects. Successful antihypertensive therapy in those younger than 80 years should not be discontinued simply because that age milestone has been crossed. Treatment of frail older patients must be individualized. Some frail survivors age 80 years or older may actually fare better with elevated systolic pressures. Pending the cognitive function substudy of Systolic Blood Pressure Intervention Trial, there is little evidence that antihypertensive treatment benefits established cognitive dysfunction. Because hypertension in middle age is a good predictor of later cognitive dysfunction, the clinical approach should be one of early prevention.

Management of hypertension in hospitalized patients.

Elevated blood pressure (BP) is a common problem in patients hospitalized for reasons other than hypertension. Unexpected elevations commonly result in calls to physicians who too often prescribe medication to reduce the numbers without evaluating the patient or determining the cause of the elevation. This may result in unnecessary and sometimes harmful treatment. Such BP elevation has many potential causes. These include anxiety, post-operative salt and volume overload, failure to administer the patient's known antihypertensive medication, inability to give oral antihypertensive medication to patients who cannot take pills by mouth, incipient heart failure, previously unrecognized renal failure, obstructive uropathy and other causes. These must be identified and treated prior to addressing only the elevated BP numbers. We present an algorithm for evaluating hospitalized patients with elevated BP in order to assist physicians in identifying the true cause of the elevation, treating the identified cause, and giving appropriate drug treatment. We also note that this is a golden opportunity for communication with the outpatient providers who will follow the patient.

Effects of nebivolol versus metoprolol on sodium sensitivity and renal sodium handling in hypertensive Hispanic postmenopausal women.

Several consistent lines of evidence indicate an association between sodium sensitivity and impaired nitric oxide bioactivity. Nevertheless, whether restoring nitric oxide in humans by pharmacological means can ameliorate sodium sensitivity has not been investigated. Because nebivolol has been demonstrated to increase nitric oxide bioactivity in both laboratory and clinical investigations, we hypothesized that nebivolol might ameliorate sodium sensitivity and improve renal sodium handling in comparison to metoprolol. We therefore conducted a randomized, 2-treatment-period crossover trial in 19 Hispanic postmenopausal women with hypertension to determine the comparative effects of nebivolol versus metoprolol on (1) 24-hour ambulatory blood pressure response to an increase in dietary sodium from 5 days of low sodium to 5 days of high sodium, (2) renal natriuretic response to a 1-L saline challenge, and (3) asymmetrical dimethylarginine. Clinic blood pressure and heart rate were significantly reduced after 4 weeks of treatment with both nebivolol and metoprolol. Twenty-four­hour mean systolic blood pressure increased sharply from low sodium to high sodium for both nebivolol and metoprolol. Nevertheless, the increases in blood pressure did not differ between the 2 drugs: 7.7 (3.1, 12.3) mm Hg with metoprolol and 9.3 (4.6, 13.9) mm Hg with nebivolol (P=0.63). Furthermore, we observed no differences between the drugs in natriuretic response to saline challenge or asymmetrical dimethylarginine. In a sodium-sensitive population, at doses sufficient to produce reductions in blood pressure and heart rate, nebivolol did not demonstrate a significant effect on sodium sensitivity or sodium handling compared with metoprolol.

Combination therapy for hypertension 2013: an update.

We provide a review of recent additions to the antihypertensive armamentarium in the form of combination therapy. These include two-drug and three-drug combinations in a single pill. There is evidence that such combinations are more efficacious than the individual components and that patient adherence to therapy is improved.

Hypertension in peritoneal dialysis patients: epidemiology, pathogenesis, and treatment.

Hypertension is prevalent in an estimated 29% to 80% of patients treated with peritoneal dialysis (PD). Cardiovascular disease represents the most common cause of mortality in this population, and hypertension (HTN) plays an important role. Volume overload is prevalent in PD patients because of liberal intake of fluids and loss of residual renal function (RRF). Noncompliance with salt restriction causes weight gain and makes HTN more difficult to manage. Physiology of the peritoneal membrane and its transport characteristics governs the ultrafiltration rate and consequently both volume and HTN. Therapeutic options for blood pressure control are ultrafiltration through the osmotic or colloid osmotic effects of dialysis solutions, salt restriction, and the use of antihypertensive medications such as diuretics, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. Loop diuretics are used to maintain urine output in nonoliguric patients. Doses may exceed 250 mg of furosemide; ototoxicity is not problematic if blood levels are monitored carefully. Preservation of RRF is important for maintaining volume control and, thereby, control of HTN.

Adherence and persistence with taking medication to control high blood pressure.

Nonadherence and poor or no persistence with taking antihypertensive medications results in uncontrolled high blood pressure, poor clinical outcomes and preventable health care costs. Factors associated with nonadherence are multilevel and relate not only to the patient, but also to the provider, health care system, health care organization, and community. National guideline committees have called for more aggressive approaches to implement strategies known to improve adherence and technologies known to enable changes at the systems level including improved communication among providers and patients. Improvements in adherence and persistence are likely to be achieved by supporting patient self-management, a team approach to patient care, technology-supported office practice systems, better methods to measure adherence, and less clinical inertia. Integrating high blood pressure control into health care policies that emphasize and improve prevention and management of chronic illness remains a challenge. Four strategies are proposed: focusing on clinical outcomes; empowering informed, activated patients; developing prepared proactive practice teams; and advocating for health care policy reform. With hypertension remaining the most common reason for office visits, the time is now.