Gender difference in response to thromboxane A2/prostaglandin H2 receptor antagonism in spontaneously hypertensive rats.
BACKGROUND
Blood pressure (BP) is typically higher in men than in women. As in humans, BP is higher in male spontaneously hypertensive rats (SHRs) than in female SHRs. The mechanism(s) responsible for the higher BP in men and male rats has not been elucidated.


OBJECTIVE
The present study tested the hypothesis that thromboxane and/or the thromboxane A(2)/prostaglandin H(2) receptor (TxR) plays a role in the gender difference in BP in SHRs.


METHODS
Male and female SHRs were treated with the TxR antagonist SQ29548 (2 microg/kg/min into the jugular vein) via minipump for 2 weeks; mean arterial pressure (MAP) and renal hemodynamic function were measured. To determine whether thromboxane played a role in the higher MAP in SHRs, male and female rats were treated with the thromboxane synthase inhibitor (TxI) furegrelate, 30 mug/kg/min, via minipump, for 2 weeks.


RESULTS
MAP was reduced with TxR antagonism in male but not in female SHRs. In addition, TxR antagonism in males caused renal vasodilation with increases in glomerular filtration rate and renal plasma flow, and reductions in renal vascular resistance. In contrast, MAP was not affected by the TxI in either males or females.


CONCLUSIONS
These data support a role for TxR, but not thromboxane, in mediating the gender difference in BP in SHRs.
Acosta Cazal
Maria Carolina
MC
Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi 39216-4505, USA.
Fortepiani
Lourdes A
LA
Santacruz
Francisco
F
Reckelhoff
Jane F
JF
D000704:Analysis of Variance; D000818:Animals; D001572:Benzofurans / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects*; D019086:Bridged Bicyclo Compounds, Heterocyclic; D005231:Fatty Acids, Unsaturated; D005260:Female; D006439:Hemodynamics / Q000187:drug effects*; D006834:Hydrazines / Q000494:pharmacology*; D008297:Male; D051381:Rats; D011918:Rats, Inbred SHR; D012737:Sex Factors; D013930:Thromboxane-A Synthase / Q000037:antagonists & inhibitors*
D001572:Benzofurans; D019086:Bridged Bicyclo Compounds, Heterocyclic; D005231:Fatty Acids, Unsaturated; D006834:Hydrazines; C045749:SQ 29548; D013930:Thromboxane-A Synthase; C039936:furegrelate