HYPERTENSION IN CB57BL/6J-MOUSE MODEL OF NON-INSULIN-DEPENDENT DIABETES-MELLITUS

The C57BL/6J (BL/6) mouse develops non-insulin-dependent diabetes mellitus (NIDDM) when fed a high fat-high simple carbohydrate (HFHSC) diet, whereas A/J mice do not. The purpose of the study was to determine whether hypertension occurred with NIDDM and whether it was sustained by sympathetic nervous system (SNS) hyperactivity. After 3 mo on an HFHSC diet with a low Na content (0.06%), awake, tail-cuff systolic blood pressure (BP) increased 20% above the control diet in BL/6 (138 +/- 3 vs. 115 +/- 4) but not in A/J (115 +/- 6 vs. 113 +/- 2 mmHg) mice. On a normal Na (0.4%)-HFHSC diet, BL/6 mice had a higher BP than on 0.06% Na (149 +/- 3 at 3 mo, 162 +/- 6 at 4.5 mo). After 1 mo on the 0.06% Na-HFHSC diet, direct BP of anesthetized BL/6 mice was 18% higher than control. The hypotensive response to interruption of SNS activity by ganglionic blockade (chlorisondamine) increased in the BL/6 mice (50%), whereas the heart rate response increased in both strains (20-30%). Analysis of variance (ANOVA) on glucose detected significant effects of strain and diet and a strain x diet interaction (P = 0.0007). At 1 or 3 mo, HFHSC-fed BL/6 mice were hyperglycemic (>11 mM) compared with diet or strain controls. The ANOVA on insulin detected strain and diet effects but not a strain x diet interaction (P = 0.3). HFHSC increased insulin above the control of 140-160 pM in A/J and BL/6 strain (20-70% at 1 mo, 400% at 3 mo). The weight gain was similar in the BL/6 and A/J mice. We conclude that 1) hypertension occurred with NIDDM in the BL/6 mouse and was sustained by SNS hyperactivity, 2) increased SNS activity to the heart was a normal response to the HFHSC diet, and 3) hypertension was not linked obligatorily to hyperinsulinemia or obesity.