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Chronic Caffeine Administration Exacerbates Renovascular, but not Genetic, Hypertension in Rats
590
DISEASES OF BLOOD VESSELS, HYPERTENSION AND RENOVASCULAR SURGERY
E:ndourology
sumption in humans with renovascular hypertension is unknown to date. J. D. S. 4 figures, 3 tables, 27 references
B. N. NOCKS, Department of Surgery, Harvard Medical School and Departments of Urology, Spaulding Hospital and Massachusetts General Hospital, Boston, Massachusetts
Renography With Captopril: Changes in a Patient With Hypertension and Unilateral Renal Artery Stenosis
CALCULUS
N. Y. State J. Med., 86: 510-511 (Oct.) 1986 The author provides an overview of the expanding field of endourology. The origin of endourology is described, which began in the early 1950s with percutaneous renal puncture and the injection of antegrade contrast materials. Percutaneous stone removal also is discussed. Successful percutaneous removal of urinary tract calculi can be expected in approximately 70 to 95 per cent of appropriately selected patients. Success rates of up to 97 per cent have been reported. The author discusses the use of ureteroscopy from 1929 and progresses to much larger series with the new rigid ureteroscopes and passage of the instruments into the upper urinary tract. The use of extracorporeal shock wave lithotripsy (ESWL), and its success and complication rates are reviewed, including sepsis in 1 to 2 per cent of the patients and perinephric hematoma documented in less than 0.5 per cent. Another complication of ESWL is obstruction of the ureter secondary to a large stone burden. The author suggests that stones greater than 2 cm. in diameter should be debulked initially with percutaneous methods and that therapy should be completed with ESWL. The article concludes with a discussion of the overview of endourology and the future of this rapidly developing field. The author speculates on the possible recurrence rate of urinary stones with new technology. The possible long-term loss of renal function with percutaneous lithotripsy and the possible long-term complications of dilation of the ureter for ureteroscopy are reviewed. J. B. F. 9 figures
DISEASES OF BLOOD VESSELS, HYPERTENSION AND RENOVASCULAR SURGERY Chronic Caffeine Administration Exacerbates Renovascular, hut not Genetic, Hypertension in Rats A. 0HNISHI, R. A. BRANCH, K. JACKSON, R. HAMILTON, I. BIAGGIONI, G. DERAY AND E. K. JACKSON, Division of Clinical Pharmacology, Departments of Pharmacology and Internal Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee
J. Clin. Invest., 78: 1045-1050 (Oct.) 1986 Recent studies demonstrated the attenuation of renin release in renovascular hypertension by the drug adenosine. With rat models the authors show that caffeine, an antagonist of adenosine receptors, greatly exacerbated renovascular hypertension but it did not influence spontaneous or genetic hypertension. The effect of caffeine was accompanied by a 7-fold increase in plasma renin activity and histological changes consistent with malignant hypertension. The hypertensive effects of caffeine were not seen in rats pre-treated with the converting enzyme inhibitor enalapril. However, the role, if any, of caffeine con-
G. G. GEYSKES, H. Y. OEI, C. B. A. J. PUYLAERT AND E. J. D. MEES, Department of Nephrology and Hypertension, University Hospital, Utrecht, The Netherlands
Arch. Intern. Med., 146: 1705-1708 (Sept.) 1986 Renal failure after antihypertensive treatment with captopril has been described in 4 patients, each with a transplanted kidney and renal artery stenosis, and in 11 patients with bilateral renal artery stenosis or renal artery stenosis in a solitary kidney. In these patients the viability of the kidney remained unaffected and renal insufficiency resolved within a short period after discontinuation of captopril administration. The cause of this renal failure is functional: a severe but rapidly reversible deterioration of the glomerular filtration rate without evident tubular damage. The decrease in the glomerular filtration rate by converting enzyme inhibition is believed to be owing not only to a further decrease of the already low arterial pressure distal to the stenosis but also, and possibly more importantly, to interruption of the autoregulation of the glomerular filtration rate. The effect of angiotensin 2 on the efferent arteriole is important for the maintenance of the filtration pressure, in particular at low arterial blood pressure. Deterioration of glomerular filtration induced by captopril also should occur in the affected kidney of patients with renovascular hypertension owing to unilateral renal artery stenosis. However, clearance studies will not reveal a unilateral loss of excretory function because the glomerular filtration rate and diuresis will be maintained by the contralateral kidney. In the patient described such a unilateral disturbance ofrenal function was present as could be demonstrated with a noninvasive method: gamma camera renography using orthoiodohippurate sodium 131iodine (1 31 I) and 99 mtechnetium diethylenetriaminepentaacetic acid (99mTc-DTPA). In a 56-year-old man with severe familial hypertension and unilateral renal artery stenosis captopril induced striking changes in the renograms of the affected kidney. After injection of orthoiodohippurate sodium 131 I, the uptake phase was un changed but the later curve showed continuous accumulation. In contrast, the uptake of 99mTc-DTPA was abolished. These changes are compatible with a cessation of filtration and maintenance of renal blood flow. After balloon dilation of the stenosis the blood pressure became lower and these changes no longer could be demonstrated. The captopril renogram may provide useful information on the dependency of hypertension on unilateral renal artery stenosis. G. P. M. 3 figures, 1 table, 9 references Acute Renal Failure" IL Management of Suspected and Established Disease
R. D. FILDES, L. E. SPRINGATE AND E. G. FELD, Department of Pediatrics, State University of New York at Buffalo, Division of Urology, Children's Hospital of Buffalo, Buffalo, New York J. Ped., 109: 567-571 (Oct.) 1986
DISEASES OF BLOOD VESSELS, HYPERTENSION AND RENOVASCULAR SURGERY
E:ndourology
sumption in humans with renovascular hypertension is unknown to date. J. D. S. 4 figures, 3 tables, 27 references
B. N. NOCKS, Department of Surgery, Harvard Medical School and Departments of Urology, Spaulding Hospital and Massachusetts General Hospital, Boston, Massachusetts
Renography With Captopril: Changes in a Patient With Hypertension and Unilateral Renal Artery Stenosis
CALCULUS
N. Y. State J. Med., 86: 510-511 (Oct.) 1986 The author provides an overview of the expanding field of endourology. The origin of endourology is described, which began in the early 1950s with percutaneous renal puncture and the injection of antegrade contrast materials. Percutaneous stone removal also is discussed. Successful percutaneous removal of urinary tract calculi can be expected in approximately 70 to 95 per cent of appropriately selected patients. Success rates of up to 97 per cent have been reported. The author discusses the use of ureteroscopy from 1929 and progresses to much larger series with the new rigid ureteroscopes and passage of the instruments into the upper urinary tract. The use of extracorporeal shock wave lithotripsy (ESWL), and its success and complication rates are reviewed, including sepsis in 1 to 2 per cent of the patients and perinephric hematoma documented in less than 0.5 per cent. Another complication of ESWL is obstruction of the ureter secondary to a large stone burden. The author suggests that stones greater than 2 cm. in diameter should be debulked initially with percutaneous methods and that therapy should be completed with ESWL. The article concludes with a discussion of the overview of endourology and the future of this rapidly developing field. The author speculates on the possible recurrence rate of urinary stones with new technology. The possible long-term loss of renal function with percutaneous lithotripsy and the possible long-term complications of dilation of the ureter for ureteroscopy are reviewed. J. B. F. 9 figures
DISEASES OF BLOOD VESSELS, HYPERTENSION AND RENOVASCULAR SURGERY Chronic Caffeine Administration Exacerbates Renovascular, hut not Genetic, Hypertension in Rats A. 0HNISHI, R. A. BRANCH, K. JACKSON, R. HAMILTON, I. BIAGGIONI, G. DERAY AND E. K. JACKSON, Division of Clinical Pharmacology, Departments of Pharmacology and Internal Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee
J. Clin. Invest., 78: 1045-1050 (Oct.) 1986 Recent studies demonstrated the attenuation of renin release in renovascular hypertension by the drug adenosine. With rat models the authors show that caffeine, an antagonist of adenosine receptors, greatly exacerbated renovascular hypertension but it did not influence spontaneous or genetic hypertension. The effect of caffeine was accompanied by a 7-fold increase in plasma renin activity and histological changes consistent with malignant hypertension. The hypertensive effects of caffeine were not seen in rats pre-treated with the converting enzyme inhibitor enalapril. However, the role, if any, of caffeine con-
G. G. GEYSKES, H. Y. OEI, C. B. A. J. PUYLAERT AND E. J. D. MEES, Department of Nephrology and Hypertension, University Hospital, Utrecht, The Netherlands
Arch. Intern. Med., 146: 1705-1708 (Sept.) 1986 Renal failure after antihypertensive treatment with captopril has been described in 4 patients, each with a transplanted kidney and renal artery stenosis, and in 11 patients with bilateral renal artery stenosis or renal artery stenosis in a solitary kidney. In these patients the viability of the kidney remained unaffected and renal insufficiency resolved within a short period after discontinuation of captopril administration. The cause of this renal failure is functional: a severe but rapidly reversible deterioration of the glomerular filtration rate without evident tubular damage. The decrease in the glomerular filtration rate by converting enzyme inhibition is believed to be owing not only to a further decrease of the already low arterial pressure distal to the stenosis but also, and possibly more importantly, to interruption of the autoregulation of the glomerular filtration rate. The effect of angiotensin 2 on the efferent arteriole is important for the maintenance of the filtration pressure, in particular at low arterial blood pressure. Deterioration of glomerular filtration induced by captopril also should occur in the affected kidney of patients with renovascular hypertension owing to unilateral renal artery stenosis. However, clearance studies will not reveal a unilateral loss of excretory function because the glomerular filtration rate and diuresis will be maintained by the contralateral kidney. In the patient described such a unilateral disturbance ofrenal function was present as could be demonstrated with a noninvasive method: gamma camera renography using orthoiodohippurate sodium 131iodine (1 31 I) and 99 mtechnetium diethylenetriaminepentaacetic acid (99mTc-DTPA). In a 56-year-old man with severe familial hypertension and unilateral renal artery stenosis captopril induced striking changes in the renograms of the affected kidney. After injection of orthoiodohippurate sodium 131 I, the uptake phase was un changed but the later curve showed continuous accumulation. In contrast, the uptake of 99mTc-DTPA was abolished. These changes are compatible with a cessation of filtration and maintenance of renal blood flow. After balloon dilation of the stenosis the blood pressure became lower and these changes no longer could be demonstrated. The captopril renogram may provide useful information on the dependency of hypertension on unilateral renal artery stenosis. G. P. M. 3 figures, 1 table, 9 references Acute Renal Failure" IL Management of Suspected and Established Disease
R. D. FILDES, L. E. SPRINGATE AND E. G. FELD, Department of Pediatrics, State University of New York at Buffalo, Division of Urology, Children's Hospital of Buffalo, Buffalo, New York J. Ped., 109: 567-571 (Oct.) 1986