Key result
Central administration of omega-conotoxin GVIA (30 pmol/kg) in conscious rabbits progressively decreased mean arterial pressure by 19 +/- 4 mmHg at 48 hours and attenuated the baroreceptor reflex.
Why the study?
Does central administration of omega-conotoxin GVIA affect cardiovascular parameters and autonomic reflexes in conscious rabbits?
Does central administration of omega-conotoxin GVIA affect cardiovascular parameters and autonomic reflexes in conscious rabbits?
Central administration of omega-conotoxin GVIA at 30 pmol/kg in conscious rabbits progressively decreases mean arterial pressure and attenuates the sympathetically mediated upper component of the baroreceptor-heart rate reflex curve.
Hypothesis-generating for central N-type blockade in hypertension; leaves open clinical translation and human safety data.
The effects of central administration of omega-conotoxin GVIA (omega-CTX), an N-type calcium channel blocker, were examined in conscious rabbits implanted with lateral intracerebroventricular (i.c.v.) cannulae. 2. Experiments were performed over 4 consecutive days. On day 1, the baroreceptor heart rate (induced by glyceryl trinitrate and phenylephrine) and Bezold-Jarisch like (elicited by serotonin) reflexes were measured before (0 h) and 2 h after central administration of omega-CTX (3 or 30 pmol/kg, i.c.v.) or vehicle. On days 2-4, resting parameters and reflexes were again monitored but no further omega-CTX was administered. 3. No change in heart rate (HR) was observed in any rabbit treatment group during the experimental period. In the vehicle (n = 6) and omega-CTX 3 pmol/kg (n = 6) groups, small falls in mean arterial pressure (MAP) of 6 +/- 2 and 10 +/- 3 mmHg, respectively, occurred between 0 and 24 h; MAP then remained stable. Baroreceptor-heart rate reflex curve parameters did not change in either of these groups during the 4 day period. 4. Following administration of omega-CTX 30 pmol/kg (n = 7), MAP decreased progressively and by 48 h had fallen by 19 +/- 4 mmHg. Also at 48 h, a 20% decrease in HR range of the baroreceptor-heart rate reflex curve was seen without any change in the lower HR plateau from the 0 h control. This indicates that there was an attenuation of the sympathetically mediated upper component of the curve while the vagally mediated component was unaffected.(ABSTRACT TRUNCATED AT 250 WORDS)
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Whorlow et al. (1994) studied Cardiovascular parameters and autonomic reflexes (n=19). omega-conotoxin GVIA (omega-CTX) vs. Vehicle was evaluated on Mean arterial pressure (MAP) and baroreceptor-heart rate reflex curve parameters. Central administration of omega-conotoxin GVIA (30 pmol/kg) in conscious rabbits progressively decreased mean arterial pressure by 19 +/- 4 mmHg at 48 hours and attenuated the baroreceptor reflex.