OMEGA-CONOTOXIN GVIA AND PRAZOSIN, BUT NOT FELODIPINE, CAUSE POSTURAL HYPOTENSION IN RABBITS

Abstract

1. The aim was to compare the effect of N-type calcium channel blockade by omega-conotoxin GVIA (omega-CTX) with alpha 1-adrenoceptor or L-type calcium channel blockade on postural adaptation in conscious rabbits. 2. Orthostatic responses were assessed by rapidly tilting the rabbits through 90 degrees for 1 min. Tilts were performed before, 30 and 60 min after i.v. bolus administration of vehicle (propylene glycol 0.17 mL/kg; n = 8), prazosin (0.5 mg/kg; n = 8), felodipine (30 micrograms/kg; n = 8) or omega-CTX (3 & 7 micrograms/kg; n = 9). 3. Prazosin, felodipine or omega-CTX caused significant falls in mean arterial pressure (MAP) with corresponding increases in heart rate (HR). Vehicle ad..