The effects of agents that modulate calcium channels were examined on arterial baroreflex sensitivity in 5 conscious dogs previously instrumented with a left ventricular (LV) pressure gauge and an arterial pressure catheter. The calcium promoter, BAY y 5959 (20(ig/kg/min x 10min, i.V.) increased mean arterial pressure by 8±4 from 9013 mmHg and decreased heart rate by 39±5 from 96±4 beats/min and increased LV dP/dt by 16891332 from 2495±160 mmHg/sec. Verapamil (a total dose of 200 ng/kg, i.v.) decreased mean arterial pressure by 812 from 91±6 mmHg and decreased LV dP/dt by 459186 from 26481241 mmHg/sec, and didn't change heart rate. Arterial baroreflex sensitivity was evaluated by calculation of pulse-interval/systolic arterial pressure (PI/SAP) slopes, elicited by intravenous nitroglycerin (NTG) (5-10 (ig/kg) and phenylephrine (PE) (5-10 ng/kg) injections. The calcium promotor increased baroreflex sensitivity significantly from 13.210.8 to 22.411.8 msec/mmHg (p<0.05) following NTG and from 19.112.1 to 33.014.7 msec/mmHg following PE (p<0.05). In contrast, verapamil decreased baroreflex sensitivity from 12.710.8 to 7.110.9 msec/mmHg (p<0.05) following NTG and from 18.612.6 to 12.012.4 msec/mmHg following PE. Thus, the calcium promotor, BAY y 5959, augments arterial baroreflex sensitivity in conscious dogs, whereas the calcium blocking agent, verapamil, exerts the opposite effect, suggesting that transmembrane calcium influx can modulate baroreflex sensitivity. The positive effects of the calcium promotor on the arterial baroreflex are of particular importance in heart failure, a state characterized by depressed baroreflex sensitivity.
|Original language||English (US)|
|State||Published - 1996|
ASJC Scopus subject areas
- Molecular Biology