Mw. Brands et al., EXAGGERATED PRESSER AND CHRONOTROPIC RESPONSE TO CHRONIC HYPERINSULINEMIA IN SH VERSUS WKY RATS, American journal of hypertension, 7(1), 1994, pp. 75-81
Insulin resistance and the sympathetic nervous system have been sugges
ted to be important factors in the blood pressure response to hyperins
ulinemia. This study was designed to investigate whether the response
to chronic hyperinsulinemia in 14-week-old SH rats (n = 6), which are
reported to be insulin resistant and to have a hyperresponsive sympath
etic nervous system, would differ from that in WKY rats (n = 5). Mean
arterial pressure (MAP) and heart rate (HR) were monitored 19 h/day by
computer. After a 4-day control period, insulin (1.5 mU/kg/min) and g
lucose (19.3 [WKY] or 13.5 [SH] mg/kg/min) were infused intravenously
for 7 days. Plasma insulin increased from 43 +/- 7 and 68 +/- 7 mU/mL
to 75 +/- 4 and 91 +/- 11 mU/mL in WKY and SH rats, respectively, with
no decrease in plasma glucose in either group. MAP during control ave
raged 99 +/- 2 and 130 +/- 4 in WKY and SH rats, respectively, and inc
reased 2 +/- 2 mm Hg above control in WKY rats and 18 +/- 4 mm Hg in S
H rats on day 1 of insulin. However, after day 2 the change from contr
ol was no longer significantly different between the groups and averag
ed 11 +/- 2 and 15 +/- 6 mm Hg above control on day 7 in the WKY and S
H rats, respectively. The change in heart rate from control was 5 +/-
5 and 21 +/- 9 beats per minute in the WKY and SH rats on day 1 of ins
ulin, and this difference also diminished with time. These results dem
onstrate that SH rats have a transiently exaggerated presser and chron
otropic response to hyperinsulinemia relative to WKY rats.