Effect of different ions at various concentrations outside the carotid-sinus on blood pressure

Libing LIU; Jie LIANG; Chunguang DUAN; Lijun SHANG; An XIE

ABSTRACT

BACKGROUND:

There are pressure sensors in carotid-sinus, which are very sensitive to blood pressure regulated by ions and play an important role in the regulation of blood pressure. But it is yet not very clear how different ions regulate the blood pressure through pressure sensors in carotidsinus.

OBJECTIVE:

To observe the effect of different ions at various concentrations outside the carotid-sinus.

DESIGN:

Self-control experiment.

SETTING:

Preclinical Experiment Center, Fourth Military Medical University of Chinese PLA.MATERIALS The experiment was accomplished in the Preclinical Experiment Center, Fourth Military Medical University of Chinese PLA from December 2000 to June 2001. Totally 18 New Zealand pure strain rabbits were provided by the Aninal Experimenting Center of Fourth Military Medical University of Chinese PLA. They were standard grade Ⅱ, of either gender and body mass was (2.0±0.2) kg.

METHODS:

The rabbits were divided into Na+, K+ and Ca2+ groups according to random numbers, and each group consisted of 6 rabbits. After anaesthesia, tracheal intubatton was performed on the rabbit, and bilateral carotid arteries were separated with carotid-sinus separated on one side and vessel intubatton performed in the other side for blood pressure measurement. Then various concentrations of Na+, K+ and Ca2+ ions were added outside the carotid-sinus with the pipette to make the carotid-sinus completed immersed in the ion solutions. The basal blood pressure and the peak value after ions addition were recorded respectively.MAIN OUTCOME

MEASURES:

The basal blood pressure and the peak value after ions addition.

RESULTS:

After Na+ (0.15, 1.5 mol/L) was added the blood pressure was(97±12), (83±17) mm Hg. It was decreased significantly compared with the basal value (106±14), (105±12) mm Hg (t=2.946, P ＜ 0.05). K+ (0.4 mol/L)decreased the blood pressure significantly [(106±12), (64±13) mm Hg, (t=13.496, P ＜ 0.01)], but other concentrations of K+ were not effective. Ca2+(0.07 mol/L) increased the blood pressure to (113±16) mm Hg compared with the basal value (103±12) mm Hg (t=-3.627, P ＜ 0.01).

CONCLUSION:

Na+, K+ and Ca2+ regulate the blood pressure by acting on the carotid-sinus directly. High concentrations of Na+ and K+ possess the effect of decreasing the blood pressure, while high concentrations of Ca2+increases it, which may be an important mechanism of blood pressure regulation.