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Despite reduction of stroke and coronary mortality rates, progression of renal disease to end stage continues to occur with increasing frequency. Recent studies emphasize common pathways of elevated arterial pressures that produce increased glomerular capillary pressures and increase filtered proteins in the urinary space. Such proteinuria, along with activation of the intrarenal renin-angiotensin system, endothelin, and inflammatory cytokines, magnifies progressive renal injury and fibrosis. Malignant forms of hypertension with severe arteriolar injury and proteinuria can be treated effectively with current antihypertensive regimens with improved patient survival. Several recent studies indicate improved renal outcomes in proteinuric diseases, generally regardless of the specific antihypertensive agent. Recent trials of hypertensive subjects with minimal proteinuria demonstrate slower rates of disease progression than that seen in subjects with proteinuria above 1 gram per day. Reduction of arterial pressures, particularly when it leads to reduced proteinuria, can slow the progression of many renal diseases.

Background: The current success of cardiac transplantation is in part attributable to the development of effective immunosuppressive agents such as cyclosporine. However, concern remains regarding the potential for cyclosporine-induced nephrotoxicity. Animal studies and early reports of renal protective effects of pentoxifylline in bone marrow transplant recipients prompted a randomized trial in cardiac transplant recipients., Methods: Twenty-nine patients were randomized to receive pentoxifylline 400 mg p.o. t.i.d. or matching placebo for 1 year after cardiac transplantation. Renal function was assessed preoperatively and at 1, 6, and 12 months postoperatively. Glomerular filtration rate and renal plasma flow were measured with iothalamate and para-aminohippurate, respectively. Serum creatinine was also measured. Ambulatory blood pressure monitoring after withdrawal of antihypertensives for 3 days was performed 12 months postoperatively., Results: Twenty-seven patients completed the study. Glomerular filtration rate rose between 1 and 6 months after transplantation, presumably due to the reduction in goal cyclosporine level in that period, and then fell modestly between 6 and 12 months, presumably due to ongoing nephrotoxic effects of cyclosporine. No difference in glomerular filtration rate or creatinine was seen between pentoxifylline and placebo groups at any interval. Renal plasma flow increased modestly between baseline and 6 months in the pentoxifylline group, but not in the placebo group, and then fell between 6 and 12 months. Serum creatinine increased between baseline and 6 months in both groups, apparently due to increased body weight. Results of 18-hr ambulatory blood pressure monitoring obtained 1 year after transplantation was not different between groups., Conclusions: Renal function declines only modestly in the first year after cardiac transplantation. Pentoxifylline did not attenuate this process and had no effect on blood pressure. The modest decline in renal function may be related to current immunosuppressive strategies.

The development of atherosclerotic cardiovascular complications is a common and serious problem for the long-term survivors of organ transplantation. Cyclosporine A plus steroid-based immuno-suppression regimens in these patients are associated with the development of hypertension, hyperlipidemia, obesity, and diabetes mellitus. Whether the new immunosuppressive agent tacrolimus (FK506) confers any advantage in terms of these cardiovascular risk factors has been less well studied. We compared serial changes in blood pressure, lipids, body weight, and glucose levels during the first 12 months after liver transplantation in patients using either cyclosporine A (n = 39) or tacrolimus (n = 24)-based immunosuppression. By 12 months, the prevalence of hypertension, hypercholesterolemia, and obesity was increased in the cyclosporine A group compared to tacrolimus: 82% versus 33%, 33% versus 0%, and 46% versus 29%, respectively (all p < .05). Triglyceride and total cholesterol levels were 196 +/- 23 versus 125 +/- 13 mg/dL and 225 +/- 9 versus 159 +/- 7 mg/dL for the cyclosporine A versus tacrolimus groups, respectively (p < .05). Cumulative posttransplant steroid dose was not related to the observed lipid changes in either group, although the increase in triglycerides was positively correlated to weight gain and diuretic use in the cyclosporine A group. The incidence of diabetes mellitus was not increased from baseline in either group. These results indicate that tacrolimus, compared to cyclosporine A, is associated with a less adverse cardiovascular risk profile in the first year after liver transplantation. Whether these differences persist and become clinically relevant to a liver transplant recipient population that is increasingly older and has more preexisting cardiovascular disease remains to be determined.

Hypertension, which develops after organ transplantation during immunosuppression with cyclosporine (CSA), is often associated with a loss of nocturnal decrease in blood pressure. Few data correlate circadian blood pressure patterns before transplant with those observed at fixed time points after transplant, or address the role of alternate immunosuppressive agents such as FK506. FK506 is unrelated structurally to CSA and less often leads to hypertension early after transplant. The present study compared nocturnal blood pressure patterns in patients with end-stage liver disease (ESLD) before transplant to those of transplant recipients receiving either FK506 (0.15 mg/kg/day) plus prednisone or CSA (2 to 3 mg/kg/day) plus prednisone and azathioprine after orthotopic liver transplantation. Overnight ambulatory blood pressure profiles were studied in 13 pretransplant ESLD patients and in 34 patients (FK506: n = 13; CSA: n = 21) treated with different steroid doses (24 +/- 11 mg/day FK506; 34 +/- 3 mg/day CSA), according to protocol, 4 weeks (range, 2 to 7 weeks) after liver transplant. Mean blood pressure and heart rate values from awake and nocturnal 5-h time blocks were compared to 13 normotensive control subjects. Patients with ESLD were normotensive and maintained a normal nocturnal blood pressure fall (125 +/- 3/74 +/- 2 mm Hg awake; 109 +/- 3/60 +/- 2 mm Hg nocturnal). Awake ambulatory blood pressures were higher in CSA patients than in FK506 patients (148 +/- 3/95 +/- 2 v 128 +/- 3/78 +/- 2 mm Hg, respectively; P < .01), despite reduced glomerular filtration rates in both transplant groups. Both immunosuppressive regimens led to a loss of nocturnal blood pressure fall, as compared to ESLD patients or normotensive controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclosporine induces hypertension and wide-spread vasoconstriction after transplantation in addition to reducing kidney function. We studied hemodynamic, renal, and hormonal effects of monotherapy with nifedipine XL (n = 37) in liver transplant recipients within a year after transplant (median, 4.4 months). Systemic hemodynamics were determined with thoracic electrical bioimpedance. Blood pressure before therapy was 172 +/- 4/108 +/- 2 mm Hg. Sixty-four percent of recipients achieved blood pressures less than 140/90 mm Hg mediated by a fall in systemic vascular resistance index (2427 +/- 245 dyne.s.cm-5.m-2 in responders versus 2905 +/- 281 in nonresponders, P < .01). Despite the fall in systemic vascular resistance, glomerular filtration rates were not changed during nifedipine therapy, as measured by both creatinine and iothalamate clearances. Urinary prostacyclin (6-ketoprostaglandin F1 alpha) was suppressed below normal from 2468 +/- 323 ng/d before transplant to 1103 +/- 99 ng/d (P < .01) after transplant and did not change during nifedipine therapy. Urinary thromboxane B2 and plasma renin activity also fell after transplant and remained low during nifedipine. These data demonstrate that nifedipine can reverse systemic vasoconstriction associated with hypertension after transplantation. Systemic effects were not transmitted to the kidney sufficiently to improve glomerular filtration rate or reverse hormonal changes within the kidney. Hence, vascular and functional regulation of the kidney was dissociated from the systemic circulation during nifedipine administration after transplantation.

Vasoconstriction and hypertension have been prominent during cyclosporin A (CSA) administration. To evaluate whether CSA modulates vascular responsiveness to pressor stimuli in the intact organism, CSA was administered via osmotic pump (10 and 20 mg.kg-1.day-1 ip vs. olive oil vehicle) for 2 wk. After 8 days, arterial pressure and dose-response relationships to norepinephrine, angiotensin II, and bradykinin were measured in conscious animals. Despite similar initial pressures, dose-response relationships were markedly attenuated to both norepinephrine and angiotensin II. Maximal responses were not affected, indicating a rightward shift without loss of peak effect. Vasodilation with bradykinin was not diminished. These changes were not evident after an acute CSA infusion at the same dose (10 mg.kg-1.day-1 over 2 h). Treatment with verapamil (0.505 mg/kg over 2 days) lowered basal arterial pressures but did not change the effects of CSA on pressor sensitivity. Despite attenuated pressor responses, renal vascular resistance was elevated and glomerular filtration diminished during CSA administration. These observations indicate that cyclosporin modifies vascular responsiveness to pressor stimuli in the rat and may explain the relative resistance of this species to cyclosporin-induced hypertension.

Sixteen patients with refractory hypertension were submitted to vigorous sodium depletion while cardiovascular homeostasis was monitored with measurements of hormonal and hemodynamic parameters and repeat saralasin tests. This regimen resulted in a negative sodium balance by an average of 300 mEq. The loss of sodium closely correlated to the decrease of body weight (r = 0.70, p less than 0.005). Blood pressure (BP) decreased from 176/166 +/- 8/3 to 155/109 +/-6/3 mm Hg. There was a significant correlation between percent increments in plasma renin activity (PRA) and the rise in plasma norepinephrine (r = 0.68, p less than 0.05) and a close negative correlation between percent increase in PRA and the ratio of fall in mean blood pressure (MAP) per unit of weight loss (r = -0.73, p less than 0.005). Thus, patients with the least percent increase in PRA demonstrated the greatest fall in BP per unit of weight loss, indicating that relative rather than absolute elevation of renin may be the factor limiting antihypertensive efficacy of sodium depletion. Sodium depletion induced increase in peripheral resistance and decrease in cardiac output, both mostly attributable to relative hyperreninemia. Indeed, the adverse hemodynamic changes were reversed by angiotensin inhibition, during which BP normalized. It is concluded that vigorous sodium depletion complemented by angiotensin blockade or suppression with sympatholytic agents improves management of otherwise refractory hypertension.

Two sets of studies were performed in 13 patients with proved adrenal pheochromocytoma to test the hypothesis that the sympathetic nervous system (SNS) is active and might contribute to the hypertensive state. Similar studies were performed in 15 additional patients considered to have essential hypertension. In the first set, 13 patients with pheochromocytoma were subjected to head-up tilt to assess the activity of the SNS. This maneuver decreased diastolic blood pressure in only two; heart rate increased appropriately in all except one. Changes in plasma norepinephrine (NE) were variable and did not correlate with changes in blood pressure (BP) and heart rate (HR). In the second set, 10 patients with pheochromocytoma were given a single oral dose of clonidine (0.3 mg) to evaluate what role, if any, the SNS might contribute to the hypertensive state. Fifteen patients with essential hypertension were studied similarly for comparison. Clonidine produced significant decreases in BP and HR but left plasma renin activity unchanged in both groups. In essential hypertension, the cardiovascular responses were accompanied by significant reductions in plasma NE. By contrast, plasma NE was unchanged in patients with pheochromocytoma, despite similar reductions in BP and HR. These results suggest that the sympathetic reflexes are intact in pheochromocytoma, and that much of the hypertension associated with these tumors may be related to increased sympathetic activity.

Interpretation of results obtained with angiotensin-converting enzyme inhibition in hypertensive patients has been obscured by the possibility of nonangiotensin-mediated mechanisms, particularly rats, we have compared the effects of converting enzyme inhibition (CEI) by oral captopril administration to those of dextrose. In this setting of constant angiotensin II levels, any apparent effects of CEI must be mediated by a nonangiotensin-related mechanism. Angiotensin II infusion at 30 ng/min increased mean blood pressure by an average of 22 mm Hg. Following 7 days of CEI, effective blockade of converting enzyme was established both by a 10-fold elevation of vasodepressor sensitivity to exogenous bradykinin and a markedly decreased plasma converting enzyme activity. On the ninth day of angiotensin II infusion, mean arterial pressure, heart rate, and plasma renin activity were not different between CEI and dextrose-treated groups. Similarly, blockade of angiotensin II by saralasin induced a comparable fall in blood pressure in both groups. Metabolic studies also revealed no long-term differences in water and food intake, weight change, or sodium and potassium metabolisms. These findings suggest that, in the continued presence of angiotensin II, there is no detectable hemodynamic or metabolic effect of chronic converting enzyme inhibition, and therefore that bradykinin plays little or no role in its long-term antihypertensive action.

Study of rat models of renovascular hypertension has been limited by the difficulty in measuring the post-stenotic pressures in conscious animals. We studied a model using inter-renal aortic coarctation (0.33 mm clip) in which post-stenotic (iliac) and systemic (carotid) pressures could be measured chronically. One-kidney-coarctation (1K-coarctation) rats (analagous to one-kidney, one clip hypertension) were compared to two-kidney-coarctation (2K-coarctation) and 1K-sham-coarctation groups. After coarctation, post-stenotic pressures fell to 40 +/- 4 mmHg then rose to normal over 5 days, concomitantly with a rise in systemic pressure to 141 +/- 6 mmHg. 1K-coarctation animals developed consistently higher post-stenotic pressures than 2K-coarctation rats after 6 weeks. Reduction of systemic pressures to normal with sodium nitroprusside induced major decrements in renal function in 1K-coarctation rats [effective renal plasma flow (ERPF): 4.32 +/- 0.40 to 1.41 +/- 0.28 ml/min; P less than 0.01; glomerular filtration rate (GFR), 1.56 +/- 0.18 to 0.42 +/- 0.33 ml/min, P less than 0.01], but not in 2K-coarctation or 1K-sham-coarctation groups. This produced an abrupt decrease in filtered sodium load, which combined with a decline in fractional sodium excretion during pressure reduction to make 1K-coarctation rats especially sensitive to fluctuations in renal artery pressure. We propose that a marked dependence upon post-stenotic perfusion pressures to maintain sodium homeostasis may be involved in sustaining hypertension in 1K-renovascular models. Inter-renal coarctation provides a valuable model for studying post-stenotic haemodynamic changes in chronically instrumented rats.

We studied renal plasma flow and glomerular filtration rate during graded blood pressure reduction induced with sodium nitroprusside infusion in 16 hypertensive patients with atherosclerotic renovascular disease. Eight patients with unilateral disease tolerated pressure reduction from 205 +/- 9 (SE)/103 +/- 2 mm Hg to 146 +/- 6/84 +/- 3 mm Hg (p less than 0.01) with no change in total renal function. In 8 other patients with bilateral renal arterial stenosis (all arteries 70% or more stenosed), similar pressure reduction produced marked but reversible decrements in plasma flow (152 +/- 28 mL/min to 66 +/- 13 mL/min; p less than 0.01) and glomerular filtration rate (38 +/- 8 mL/min to 16 +/- mL/min; p less than 0.01). In 4 patients restudied after revascularization, sensitivity of renal function to pressure changes was no longer present. These data indicate that vascular stenosis to the entire renal mass may limit function and provide a means for evaluating patients at risk for loss of renal function during antihypertensive therapy.

Changes in blood pressure, renal function, and fluid balance were studied in 12 patients receiving intravenous recombinant interleukin-2 (IL-2) (100,000 units/kg every eight hours) over five days for treatment of metastatic melanoma and renal and colorectal cancers. The IL-2 regimen produced progressive hypotension, azotemia, and sodium avidity (fractional excretion of sodium = 0.20 +/- 0.07 percent) despite massive fluid administration (mean: 18.4 liter per five days) and weight gain (mean: 4.0 kg). Plasma renin activity rose. Hypoalbuminemia developed rapidly (3.6 +/- 0.1 g/dl to 2.2 +/- 0.1 g/dl, p less than 0.01) with widespread edema formation despite normal central venous pressures. Hematocrit did not change during the IL-2 period, consistent with a "capillary-leak." Hemodynamic and renal functional changes reversed after the IL-2 regimen was discontinued, but hypoalbuminemia and elevated urinary n-acetyl-glucosaminidase levels persisted after six days. These studies demonstrate widespread hemodynamic and vascular effects of IL-2 administration that limit its safe use and suggest a possible role for the lymphokine in mediating cardiovascular instability under other circumstances, such as endotoxic shock.

Understanding the sequence of events responsible for pressure-related natriuresis and their pathophysiologic alterations may be useful in distinguishing various types of essential hypertension of renal origin. The perturbation of a distal step in the sequence is likely to be reflected in a simple physiologic defect. For instance, pathophysiologic alterations in the medullary production of prostaglandin E2 might directly influence natriuresis and diuresis because of its modulatory effect on tubular reabsorption of sodium and water. Perturbation of more proximal steps in the sequence could influence all the distal events as well. For instance, prostaglandin I2 and endothelium-derived relaxing factor may be produced by the preglomerular vasculature in response to alterations in renal perfusion pressure and may modulate the release of renin from the juxtaglomerular cells. Thus, variations in the production of prostaglandin I2 or endothelium-derived relaxing factor may be reflected by various renal vascular, tubular, and systemic homeostatic events related to the renin-angiotensin system.

This article focuses on the relationships between blood pressure and kidney transplant recipients. As more patients now reach end-stage kidney disease with large burdens of cardiovascular disease, more attention is being focused upon managing cardiovascular risk than ever before. Death with a functioning allograft, usually related to cardiovascular disease, is now one of the leading causes of graft loss. As a result, management of post-transplant hypertension has become an important component of the long- term medical care of the transplant recipient.