TY - JOUR
T1 - Area postrema lesion attenuates the long-term hypotensive effects of losartan in salt-replete rats
AU - Collister, John P.
AU - Osborn, John W.
PY - 1998/2
Y1 - 1998/2
N2 - We reported that the AT1 receptor antagonist losartan decreases arterial pressure in sodium-replete rats and that this response is attenuated in area postrema-lesioned (APx) rats (J.P. Collister, B. J. Hornfeldt, and J. W. Osborn. Hypertension 27: 598-606, 1996). In that study, food intake for the 3-wk period after sham lesion was restricted to that observed in APx rats. Food-restricted sham rats had lower arterial pressures and attenuated responses to losartan compared with control rats fed ad libitum. The present study examined whether these differences persisted months, rather than weeks after APx or sham lesions. Losartan was administered for 10 days to APx and two groups of sham rats 3 mo after APx or sham surgery. The first sham group was food restricted (SFR) for 3 wk after surgery, whereas the second sham group was allowed ad libitum (SAL) access to food. By day 8 of losartan administration, both sham groups demonstrated a marked hypotension (SFR: -38 ± 4; SAL: -33 ± 4 mmHg). This response was attenuated (P < 0.05) on the same day in APx rats (- 17 ± 3 mmHg). This trend continued throughout days 9 and 10. Because both sham groups responded similarly to losartan (yet significantly different from APx rats), these results demonstrate that transient decreases in food intake do not affect the response to losartan if rats are allowed an adequate recovery period. We conclude that the area postrema mediates part of the long-term hypotensive effects of AT] receptor blockade in the conscious rat.
AB - We reported that the AT1 receptor antagonist losartan decreases arterial pressure in sodium-replete rats and that this response is attenuated in area postrema-lesioned (APx) rats (J.P. Collister, B. J. Hornfeldt, and J. W. Osborn. Hypertension 27: 598-606, 1996). In that study, food intake for the 3-wk period after sham lesion was restricted to that observed in APx rats. Food-restricted sham rats had lower arterial pressures and attenuated responses to losartan compared with control rats fed ad libitum. The present study examined whether these differences persisted months, rather than weeks after APx or sham lesions. Losartan was administered for 10 days to APx and two groups of sham rats 3 mo after APx or sham surgery. The first sham group was food restricted (SFR) for 3 wk after surgery, whereas the second sham group was allowed ad libitum (SAL) access to food. By day 8 of losartan administration, both sham groups demonstrated a marked hypotension (SFR: -38 ± 4; SAL: -33 ± 4 mmHg). This response was attenuated (P < 0.05) on the same day in APx rats (- 17 ± 3 mmHg). This trend continued throughout days 9 and 10. Because both sham groups responded similarly to losartan (yet significantly different from APx rats), these results demonstrate that transient decreases in food intake do not affect the response to losartan if rats are allowed an adequate recovery period. We conclude that the area postrema mediates part of the long-term hypotensive effects of AT] receptor blockade in the conscious rat.
KW - Angiotensin II
KW - Chronic arterial pressure regulation
KW - Circumventricular organ
KW - Food restriction
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U2 - 10.1152/ajpregu.1998.274.2.r357
DO - 10.1152/ajpregu.1998.274.2.r357
M3 - Article
C2 - 9486292
AN - SCOPUS:0031990587
SN - 0363-6119
VL - 274
SP - R357-R366
JO - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
JF - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
IS - 2 43-2
ER -