Intrarenal hemodynamic changes after captopril test in patients with type 2 diabetes: a duplex Doppler sonography study.
OBJECTIVE
ACE inhibitors are known to be effective in preventing the progression of diabetic nephropathy. Activation of the renin-angiotensin system (RAS) is reported to contribute to intrarenal hemodynamic abnormality in diabetic patients. We examined whether RAS blockade by captopril induces intrarenal hemodynamic changes in normotensive patients with type 2 diabetes.


METHODS
The patients ranged in age from 40 to 65 years (20 men and 20 women). A total of 15 age- and sex-matched healthy individuals served as control subjects. Resistive index (RI) of interlobar arteries was examined by duplex Doppler sonography before and after the oral captopril (25 mg) test.


RESULTS
At baseline, no significant differences in RI values or plasma renin activity (PRA) were seen between the patients and healthy subjects. In healthy subjects, the RI values after the captopril test were significantly higher than baseline values (P < 0.01). However, in patients with type 2 diabetes, both with normoalbuminuria and microalbuminuria, RI values after the test were significantly lower than baseline values (P < 0.001). There were significant negative correlations between DeltaRI value and HbA1c (r = -0.458, P < 0.005) and between DeltaRI value and baseline PRA in diabetic patients (r = -0.339, P < 0.05). Multiple regression analysis showed that HbA1c and baseline PRA significantly and independently affected the magnitude of decrease in RI values after captopril administration in diabetic patients (R2 = 0.391, P < 0.0001).


CONCLUSIONS
These results indicate that the intrarenal RAS may be activated in diabetic patients, that such activation may be affected by poor glycemic control, and that blockade of RAS activation by ACE inhibitor reduces intrarenal vascular resistance in diabetic patients. The results emphasize the beneficial effects of ACE inhibition in improving intrarenal hemodynamics in diabetic patients.
Taniwaki
Hiromichi
H
Department of Metabolism, Endocrinology, and Molecular Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan.
Ishimura
Eiji
E
Kawagishi
Takahiko
T
Matsumoto
Naoki
N
Hosoi
Masayuki
M
Emoto
Masanori
M
Shoji
Tetsuo
T
Shoji
Shigeichi
S
Nakatani
Tatsuya
T
Inaba
Masaaki
M
Nishizawa
Yoshiki
Y
D000328:Adult; D000450:Aldosterone / Q000097:blood; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000008:administration & dosage*; D001794:Blood Pressure / Q000187:drug effects; D002216:Captopril / Q000008:administration & dosage*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000000981:diagnostic imaging; D003928:Diabetic Nephropathies / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000517:prevention & control*; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D012079:Renal Circulation / Q000187:drug effects*; D012083:Renin / Q000097:blood; D014463:Ultrasonography; D014655:Vascular Resistance / Q000187:drug effects
D000450:Aldosterone; D000806:Angiotensin-Converting Enzyme Inhibitors; D002216:Captopril; D006442:Glycated Hemoglobin; D012083:Renin