Effects of antihypertensive therapy on platelet cytosolic calcium responses to low density lipoprotein cholesterol

This study examines the effects of antihypertensive therapy on platelet cytosolic calcium [Ca2+]i responses to low-density lipoprotein cholesterol (LDL) and vasopressin (AVP) in 15 patients (50-80 years) participating in the Hypertension Optimal Treatment International Study. All patients (diastolic blood pressure (DBP) > or = 100 mm Hg and < or = 115 mm Hg) were treated with the calcium antagonist felodipine (10 mg p.o.) with or without addition of enalapril (up to 20 mg daily as needed) to lower diastolic pressures to < 85 mm Hg. This antihypertensive therapy lowered DBP (104 +/- 0.8 to 78 +/- 1.6 mm Hg, P < 0.0001), but had no effect on basal [Ca2+]i or AVP-stimulated [Ca2+]i responses. Basal platelet [Ca2+]i following antihypertensive therapy (49 +/- 3.4 ng/ml) were not different from those prior to therapy (52 +/- 4.7 ng/ml). Additionally, [Ca2+]i responses to AVP following therapy (554 +/- 74 units) were not different from those prior to treatment (595 +/- 49 units). Following antihypertensive therapy, [Ca2+]i responses to 200 micrograms/ml of LDL were decreased fourfold (P < 0.05). These results suggest that antihypertensive therapy with a calcium channel blocker may potentially impact the atherogenic process by reducing the platelet [Ca2+]i rise, and potentially the aggregatory response, to LDL.

Effects of metformin on tyrosine kinase activity, glucose transport, and intracellular calcium in rat vascular smooth muscle

Metformin enhances peripheral insulin action and reduces blood pressure in hypertensive rats. Our group has previously reported that insulin and insulin-like growth factor I (IGF-1) attenuate both agonist-induced vascular smooth muscle cell (VSMC) contraction and associated increases in cytosolic free calcium ([Ca]i). Thus, changes in insulin actions may explain in part metformin's vascular effects. However, metformin's mechanism of action at the vasculature had not been elucidated. Therefore, the purpose of this study was to determine whether metformin evokes alterations in VSMC insulin and IGF-I receptors, glucose transport, and/or [Ca]i. We quantitated hormone binding and tyrosine kinase (TK) activity in partially purified insulin and IGF-I receptors prepared from metformin-treated (100 microM) and control rat aortic VSMC in culture. Glucose transport was assessed by 2-deoxyglucose uptake. Metformin exposure for 24 h 1) increased basal TK activity (metformin, 3.49 +/- 0.39; control, 1.77 +/- 0.39 pmol 32P incorporated/mg protein; P < 0.01) without changes in insulin-or IGF-I stimulated TK activity, 2) increased 2-deoxyglucose transport in a dose-dependent manner, 3) decreased thrombin-induced elevation in [Ca]i (metformin, 10.3%; control, 35.3% over basal; P < 0.05), These insulin/IGF-I-like effects of metformin may help explain some of its vascular actions.

Diabetes mellitus and associated hypertension, vascular disease, and nephropathy. An update

Because considerable important information has been published since our previous review, this update concentrates on new findings with regard to cardiovascular and renal risk factors contributing to the striking morbidity and mortality of these coexisting diseases. For example, a large body of investigative data has recently emerged suggesting or delineating a pathogenic role for hyperglycemic-related glycosylation and oxidation of lipoproteins and vascular and renal tissues. Great strides have recently been made in the understanding of platelet, coagulation, lipoprotein, and endothelial abnormalities in the pathogenesis of cardiovascular and renal disease associated with diabetes mellitus and hypertension. Major progress has been made in clarifying the pathophysiology of glomerulosclerosis and other processes involved in the progression of diabetic nephropathy. Furthermore, accumulating data surveyed in this review address new and promising pharmacological interventions that specifically address these pathophysiological mechanisms.

Metabolic abnormalities in cardiac ischemia

Epidemiologic studies have shown a variety of metabolic abnormalities to be risk factors for coronary heart disease. Many of these metabolic risk factors coexist and may have as a common denominator the presence of insulin resistance and hyperinsulinemia. Indeed, clinical studies have demonstrated relationships among blood pressure levels, plasma insulin, fibrinogen, plasminogen activator inhibitor, factor VIII, triglycerides, and total cholesterol levels and other metabolic risk factors. Individuals with hyperinsulinemia generally have low levels of high-density lipoprotein, plasminogen activators, and endothelial relaxing factors as well. New pharmacologic and hygienic treatment strategies that enhance insulin sensitivity and help correct lipoprotein metabolism and other metabolic abnormalities will be critical in maximizing coronary risk reduction in persons with hypertension, diabetes mellitus, or a family history of premature coronary heart disease.

Erythrocyte insulin and insulin-like growth factor-I receptor tyrosine kinase activity in hypertension in pregnancy

We have shown that preeclampsia is associated with insulin resistance. In the present study, we examined young normal, preeclamptic (PE), and gestational hypertensive (GH) nulliparous African-American women at term to investigate cellular determinants of this resistance and insulin and insulin-like growth factor-I (IGF-I) binding to partially purified erythrocyte receptors and receptor tyrosine kinase activity (TKA). Blood pressure was significantly elevated in PE and GH subjects as compared with controls. Insulin binding was similar in number and affinity in the three groups (femtomoles per microgram). IGF-I binding was increased in PE subjects as compared with either normals or GH subjects (0.2 +/- 0.02, 0.15 +/- 0.01, and 0.14 +/- 0.02 fmol/microgram protein). Insulin receptor TKA was increased in PE subjects as compared with normals when assessed either per microgram protein or per femtomole insulin binding (P < .01). In contrast, IGF-I-potentiated TKA was elevated in PE subjects only when assessed per microgram protein (P < .03). Thus, the increased number of IGF-I receptors in erythrocytes of PE subjects yields a net increase in receptor tyrosine kinase. Also, there is an augmentation of insulin receptor TKA in PE subjects. Together, these two alterations may be a compensatory mechanism for the insulin resistance associated with hypertensive diseases of pregnancy.

Effect of amlodipine on left ventricular mass in the Amlodipine Cardiovascular Community Trial

As part of the Amlodipine Cardiovascular Community Trial (ACCT), which was a large multicenter study designed to assess the effects of the calcium channel blocker amlodipine besylate (Norvasc) as monotherapy for treatment of mild to moderate hypertension, we sought to determine the effects of amlodipine on regression of left ventricular (LV) hypertrophy (LVH). The study began with a 2-week placebo run-in period (baseline), before which antihypertensive drugs had been discontinued. Amlodipine was then administered at 5-10 mg/day during a 4-week titration/efficacy period. Patients achieving a goal diastolic blood pressure (DBP) of < or = 90 mm Hg or a decrease in DBP of > or = 10 mm Hg entered a 12-week maintenance phase and had the option to continue long-term therapy thereafter. Echocardiograms were obtained in a subset of patients at the end of the baseline period. In patients with LVH at baseline, echocardiograms were repeated at the end of 16 weeks of therapy (week 18), and at 42 weeks in patients continuing long-term therapy. Thirty-seven percent of 124 hypertensive patients screened for LVH at baseline had LVH detected on echocardiograms. Blacks had a higher incidence of LVH (64%) as compared with whites (34%, p < 0.05). Patients with LVH were more likely to have a higher baseline systolic BP (SBP) and DBP. Their sitting SBP and DBP decreased significantly from a mean of 163/102 mm Hg at baseline to 139/86 mm Hg with amlodipine therapy at week 18 (p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Quinapril reduces microalbuminuria in essential hypertensive and in diabetic hypertensive subjects

To investigate the metabolic and renal effects of the nonsulfhydryl, tissue-active ACE inhibitor quinapril in diabetes and in hypertension, we studied 30 essential hypertensives and 24 non-insulin-dependent (type II) diabetic (NIDDM) subjects with hypertension. Systolic and diastolic blood pressures, plasma glucose, and insulin responses to an oral glucose load (75 g), lipid profile, and urinary albumin excretion were evaluated before and after 8 weeks' administration of quinapril (10 to 40 mg/day). Quinapril produced a significant and comparable reduction of arterial blood pressure in both groups. Mean arterial pressure decreased from 114.8 +/- 0.9 to 94.2 +/- 1.1 (-17.9 +/- 1.5%) in the essential hypertensive group and from 118.4 +/- 1.6 to 96.2 +/- 1.4 (-18.4 +/- 1.6%) in the diabetic hypertensive group. In both essential hypertensives and diabetic-hypertensive subjects with microalbuminuria, quinapril significantly and comparably reduced the urinary albumin excretion rate (UAE); UAE decreased from 32.5 +/- 5.5 micrograms/min to 14.7 +/- 3.7 micrograms/min (P < .05 v baseline) in the diabetic-hypertensive group and from 27.5 +/- 3.0 micrograms/min to 11.6 +/- 2.7 micrograms/min (P < .05 v baseline) in the essential hypertensives. Altogether, a direct correlation was found between the initial level of UAE and the UAE reduction after quinapril (delta UAE) (r = 0.706, p < .05). Insulin and glucose responses to an oral glucose tolerance test and the lipid profiles were not modified by quinapril treatment. The results confirm that quinapril is an effective antihypertensive agent that additionally reduces microalbuminuria in both hypertensive diabetics and in patients with essential hypertension, without altering insulin sensitivity and lipid profiles.

Relative androgenicity, blood pressure levels, and cardiovascular risk factors in young healthy women

To test the hypothesis that androgens may play a role in the pathogenesis of atherosclerosis and hypertension, we investigated the association of delta 5 dehydroepiandrosterone sulfate [DHEAS]) and delta 4 (free testosterone [FT]) androgens with the resting, seated blood pressure (BP) levels and cardiovascular risk factors in 280 young, healthy women 18 to 24 years of age. After application of multiple regression analysis, systolic BP was positively and independently correlated with the ratio of dehydroepiandrosterone sulfate to free testosterone (DHEAS/FT), fasting insulin levels, and the diastolic BP with DHEAS/FT only. The DHEAS/FT ratio proved to be a stronger predictor of the BP levels than either hormone alone. Further, uric acid concentrations and HDL/total cholesterol ratio were independently correlated with both FT and body mass index in these young women. Serum triglycerides were independently correlated with FT and central body fat distribution. These data suggest that serum androgen concentrations are important independent predictors of cardiovascular risk factors and that the ratio of dehydroepiandrosterone sulfate to free testosterone ratio is an independent predictor of blood pressure levels in young women.

A multicenter comparison of adverse reaction profiles of isradipine and enalapril at equipotent doses in patients with essential hypertension

A multicenter, randomized, double-blind trial compared the safety and efficacy of the dihydropyridine isradipine with the angiotensin-converting enzyme (ACE) inhibitor enalapril given twice daily for mild hypertension. 160 patients received either isradipine (starting at 1.25 mg twice daily) or enalapril (starting at 2.5 mg twice daily) for 10 weeks. The dosage was increased if the average sitting diastolic blood pressure was > 90 mm Hg. Significantly greater mean reductions in systolic blood pressure were seen after 2, 6, and 8 weeks of isradipine. However, by the end of the trial, 83% of patients receiving isradipine and 78% receiving enalapril showed a decrease of at least 5 mm Hg in sitting diastolic blood pressure to a level below 96 mm Hg. Possible or probable drug-related adverse effects were reported in 36% of patients showing a good antihypertensive response to isradipine, and in 30% of those who responded to enalapril. There was a trend for a lower frequency of adverse effects in isradipine non-responders (25%) and a higher frequency in enalapril non-responders (43%). Pruritus, dizziness, edema, and fatigue were reported more often with isradipine, and cough and changed bowel habits were more common with enalapril. The relationship between the pattern of adverse effects and the extent of blood pressure reduction may be dependent on the mechanism of action of a drug. In responders, isradipine and enalapril showed differing patterns, but a similar overall incidence of adverse effects.

Doxazosin lowers blood pressure and improves insulin responses to a glucose load with no changes in tyrosine kinase activity or insulin binding

alpha-Adrenergic blockers have shown favorable metabolic effects. We evaluated the glucose and insulin responses to a glucose load and lipid profiles in 36 diabetic hypertensive patients before and after 8 weeks of doxazosin administration. To evaluate insulin action at the cellular level, erythrocyte insulin binding and tyrosine kinase (TK) activity were measured in 12 of these patients. Systolic and diastolic blood pressures decreased significantly (P < .0001) after 8 weeks of doxazosin therapy. Doxazosin administration significantly reduced the integrated insulin response (area under the curve [AUC]-insulin: 6093 +/- 894 to 5260 +/- 807; P = .04) and the insulin/glucose index (I/G) at 90 and 120 min after a glucose load (at 90 min, 0.230 +/- 0.055 v 0.180 +/- 0.04, P < .05; at 120 min, 0.275 +/- 0.071 v 0.173 +/- 0.036, P < .05). HDL3 level increased from 31.1 +/- 1.5 mg% to 34 +/- 1.6 mg% (P < .05) after doxazosin. Erythrocyte insulin binding and tyrosine kinase activity were not significantly altered after doxazosin. No significant correlation was found between the insulin or glucose responses and the insulin receptor binding or tyrosine kinase activity before and after treatment.

Effects of estradiol and progesterone on platelet calcium responses

We investigated the effects of 17 beta-estradiol (beta E2), alpha-estradiol (alpha E2), and progesterone (P) on baseline and vasopressin (AVP)-induced [Ca2+]i in human platelets obtained from healthy male and female volunteers. Platelets were treated with beta E2, alpha E2, P, or ethanol vehicle for 30 min at 37 degrees C. In males, both beta E2 and P at 10(-5) mol/L reduced the AVP-induced rise in [Ca2+]i, to 72 +/- 3% (mean +/- SEM) and 53 +/- 3%, respectively. However, at 10(-6) mol/L only beta E2 had a significant effect (P < .02). In females, 10(-6) and 10(-5) beta E2 reduced the AVP response to 85.3 +/- 4.6% and 80.8 +/- 5.4% of control values, respectively. Progesterone (10(-6) and 10(-5) mol/L) reduced the AVP response to 83.8 +/- 5.1% and 60.3 +/- 2.0% of control values, respectively. The inactive estrogen alpha E2 had no effect on basal or AVP-induced rise in [Ca2+]i in either subject population, suggesting hormonal specificity. Neither beta E2 nor P affected baseline [Ca2+]i in either population. Thus, by attenuating [Ca2+]i responses in platelets, beta E2 and P may modulate platelet aggregation and atherosclerosis.

Hyperinsulinemia and insulin resistance are associated with preeclampsia in African-Americans

There is evidence that hyperinsulinemia and insulin resistance play a role in the development of hypertension. Accordingly, in our ongoing longitudinal study of pregnancy-induced hypertension, we have measured fasting levels of insulin and glucose at 18 to 25 weeks gestation in 140 nulliparous African-American women followed prospectively to delivery. To test the hypothesis that hyperinsulinemia may be related to the development of preeclampsia, discriminant analysis of mean arterial pressure (MAP), fasting plasma insulin levels, insulin to glucose ratios, and left lateral forearm vascular resistance were examined as predictors of preeclampsia. Statistical analysis controlled for two factors known to be related to insulin levels, gestational age and pregestational body mass index. Gestational hypertensives were not different with regard to blood pressure and metabolic factors from normals and thus were placed in the control group. Women who subsequently developed preeclampsia had mean (+/- SE) fasting plasma insulin levels of 51.0 +/- 12.0 microU/mL at 20 weeks and controls had values of 29.0 +/- 2.8. Only MAP [F(4,135) = 8.8, P < .01] and insulin [F(1,135) = 6.5, P < .05] were related to the development of preeclampsia [F(4,135) = 4.39, R2 = 11.5%]. The finding that elevated second-trimester insulin levels characterize the subsequent development of preeclampsia with control for increased MAP supports the hypothesis that hyperinsulinemia and associated insulin resistance may contribute to the pathogenesis of preeclampsia.

Increased basal arterial smooth muscle glucose transport in the Zucker rat

Insulin has recently been reported to stimulate glucose transport in vascular smooth muscle cells (VSMC). This observation suggests a role for this hormone in hypertension associated with insulin resistance. To determine whether VSMC glucose transport abnormalities exist in a state of insulin resistance, we studied basal and insulin-stimulated glucose transport in VSMC derived from Zucker lean (normotensive, insulin sensitive) and obese (hypertensive, insulin resistant) rats. Basal glucose transport, as measured by tracer quantities of [3H]2-deoxyglucose, was 4.2 +/- 0.8 and 7.4 +/- 0.9 fmol/10(6) cells/min for lean and obese cells, respectively (P < .05). Kinetic analyses utilizing variable concentrations of unlabeled 2-deoxyglucose in the media revealed that increased transport in the obese rat was due to an increased Vmax of the transporter system: Vmax = 5.9 +/- 0.8 and 12.1 +/- 1.2 fmol/10(6) cells/min for lean and obese cells, respectively (P < .05); no changes in Km were noted for the two populations: Km = 1.14 +/- 0.24 and 0.96 +/- 0.10 mmol/L. Insulin (10 microU/mL) increased the Vmax of the transporter in both preparations, but greater stimulation was seen in the lean VSMC: 32 +/- 4.8% v 11.5 +/- 2.1% (P < .05). Insulin had no effect on the Km of the transporter in either strain. These data suggest that increased basal glucose transport in obese VSMC may predispose the vessel to increased glucose-mediated events, while blunted insulin-stimulated glucose transport in these cells mirrors insulin-resistant glucose disposal in other tissues of the obese rat.

In vitro relaxation of phenylephrine- and angiotensin II-contracted aortic rings by beta-estradiol

In vivo studies suggest that 17 beta-estradiol (beta E) may regulate vascular tone. Results of recent studies suggest that beta E exerts rapid effects on intracellular calcium, possibly via cell surface receptors, distinct from conventional nuclear receptors for steroids. The present study was designed to determine whether beta E acutely modifies vascular smooth muscle contractile responses to phenylephrine (PE) and angiotensin II (AII). In experiments on tonic responses of aortic rings to 5 x 10(-8) mol/L PE, cumulative additions of beta E reduced tension at concentrations > 10(-6) mol/L. Contractile dose responses to PE were determined in rat aortic rings in absence of sex hormones and then after exposure to beta E (5 x 10(-6) mol/L, n = 6) or vehicle (ETOH, n = 6) for 30 min. beta E increased ED50 and reduced maximal responses. Application of 5 x 10(-6) mol/L beta E for 30 min also reduced the contractile response to 1 mmol/L AII from 69 +/- 4% (vehicle) to 47 +/- 6% (estradiol) of maximal KCl contraction (P < .025, n = 7). These data suggest that beta E acutely attenuates vasoconstrictor responses to PE as well as to AII, possibly by an effect exerted at the cell membrane level.

Hypertensive disorders of pregnancy in southwestern Navajo Indians

BACKGROUND

The Navajos are the largest Native American tribe. They, like other Native Americans, appear to be in an "epidemiologic transition" and are accordingly experiencing increased rates of hypertension, diabetes, and obesity.

METHODS

A retrospective chart review of all pregnancies in 1991 at the Crownpoint Indian Health Service Facility in Crownpoint, NM, was conducted to determine the prevalence of hypertensive disorders of pregnancy in this Navajo population.

RESULTS

Seventy-five (12.6%) of 594 pregnancies were associated with a hypertensive disorder. There were 18 individuals who developed gestational hypertension and 10 individuals with chronic hypertension that persisted during pregnancy. There were 46 women (7.7%) who developed preeclampsia and one woman (0.3%) who developed eclampsia. Eight women (1.4%) with chronic hypertension developed superimposed preeclampsia during pregnancy. Thus, 12.3% of these pregnancies in Navajo women were associated with the development of, or worsening, hypertension, and there was a prevalence of preeclampsia of 9.1%.

CONCLUSION

The Navajos exhibit a high prevalence of pregnancy-related hypertension and preeclampsia.

Postpartum blood pressure and insulin sensitivity in African-American women with recent preeclampsia

Pregnancy-induced hypertension and preeclampsia are relatively common in nulliparous, inner-city, African-American, pregnant women and contribute to considerable maternal, fetal, and neonatal morbidity and mortality in that population. Recently, insulin resistance has been related to the development of hypertension in young African-Americans and hyperinsulinemia and elevated insulin-to-glucose ratios, suggesting insulin resistance, have been demonstrated in women with preeclampsia. To investigate whether insulin resistance existed postpartum and, therefore, independently of the pregnant state, the hyperinsulinemic, euglycemic technique was used 3 to 6 months postpartum to assess insulin sensitivity in 10 young, black, primiparous, inner-city women with recent preeclampsia and seven age-, weight- and body-mass-index-matched black women with healthy pregnancies. The age, weight, body-mass index, waist-to-hip ratio, the duration since parturition, and fasting plasma glucose and insulin were similar in the preeclamptic and control groups. During the clamp procedure, the insulin levels and mean diastolic blood pressure and mean arterial pressure were also similar for both groups; however, the mean systolic blood pressure of the preeclamptic group (123 +/- 3 mm Hg) was higher than that of the control group (114 +/- 2 mm Hg) (P < .05). Insulin-stimulated glucose disposal was not different between the preeclamptic (5.6 +/- 0.3 mg/kg/min) and control groups (5.7 +/- 0.7 mg/kg/min). This suggests that the elevation in postpartum systolic blood pressure may reflect a persistent abnormality of blood pressure homeostasis which is not associated with insulin resistance.

Effects of pioglitazone on calcium channels in vascular smooth muscle

Pioglitazone, an insulin-sensitizing, antidiabetic agent, has blood pressure-lowering effects in insulin-resistant hypertensive rats and attenuates growth factor-induced increases of intracellular Ca2+ in rat aortic vascular smooth muscle cells. To determine whether modulation of voltage-dependent Ca2+ channels plays a role in this association, we investigated the effects of pioglitazone on voltage-dependent current in cultured rat aortic (a7r5) and freshly dissociated rat tail artery vascular smooth muscle cells. Both cell types were studied with whole-cell patch-clamp techniques. Current through L-type Ca2+ channels was elicited with a voltage ramp in the presence of Ba2+ substituted for Ca2+. T-type Ca2+ current was studied using a two-pulse protocol that enabled the isolation of transient current. In a7r5 vascular smooth muscle cells, 2-minute application of pioglitazone (5 and 10 mumol/L) reduced L-type current by 7.9 +/- 1.0% (n = 8) (mean +/- SEM, number of cells) and 14.5 +/- 3.0% (n = 9) (P < .01, two-tailed paired t test), respectively. In contrast, 2-minute application of pioglitazone had no significant effect on T-type Ca2+ current. In freshly dissociated tail artery vascular smooth muscle cells, 2-minute application of 10 mumol/L pioglitazone had an insignificant effect (4.8 +/- 5.6% reduction); however, 25 mumol/L pioglitazone reduced L-type current by 27.3 +/- 7.2% (n = 5) (P < .01). Two-minute application of 0.1% or 0.2% dimethyl sulfoxide (vehicle) alone had no significant effects on currents in either type of vascular smooth muscle cell.(ABSTRACT TRUNCATED AT 250 WORDS)

Paralytic ileus as a result of diltiazem treatment

Diltiazem is a widely used calcium channel blocker, and has been found to be effective in the treatment of hypertension, stable, variant and unstable angina, as well as oesophageal spasm. Calcium channel antagonists have been shown to diminish the contractility of gut smooth muscle, but have not as yet been reported to cause clinically significant inhibition of gut motility when used alone. We report a case of reversible functional intestinal obstruction, immediately following diltiazem treatment in a patient with ischaemic heart disease.

Cost effectiveness of 24-hour ambulatory blood pressure monitoring in evaluation and treatment of essential hypertension

We wanted to determine if use of ambulatory blood pressure monitoring (ABPM) was cost effective, preventing unnecessary drug therapy in patients misdiagnosed as having essential hypertension, with elevated office blood pressures and normal ambulatory blood pressure. To address this issue we surveyed costs to the patient for antihypertensive drug therapy in 1990 of five local pharmacies in southeastern Michigan. Patients studied (n = 192) were seen in a private, general internal medicine practice in rural southeastern Michigan and received ABPM to assess the presence of hypertension and the adequacy of blood pressure treatment. We ascertained the average, minimal, and maximal drug cost to the patient per unit dose at the local pharmacies. The average yearly cost for patients on antihypertensive medications at pharmacies in southwestern Michigan was $578.40, with figures varying from $94.90 to $4361.75. Although there is no standard reimbursement amount for ABPM, at $188 per monitoring, the cost of monitoring this entire group of patients would offset exactly the cost of medication for the group of patients found to have only office hypertension. As such, third-party insurance carriers should consider reimbursement for ABPM in hypertension to decrease pharmaceutical cost and its attendant potential side effects. In conclusion, our study results suggest that ABPM is cost effective in an outpatient setting in preventing unwarranted drug therapy and the inappropriate diagnosis of hypertension.