A new blood pressure measuring apparatus equipped with a microcomputer system for conscious rats.

In order to measure the systolic blood pressure of conscious rats without thermal stress, a highly sensitive pulse sensor was developed using a light-emitting diode-photo diode system. The combination of this pulse sensor and microcomputer system led to the development of a six-channel automatic blood pressure measuring apparatus for rats. It can measure the systolic tail arterial pressure of conscious rats at 28-30 degrees C. The relationship between direct carotid arterial pressure (Y) and indirect tail arterial pressure (X) in conscious spontaneously hypertensive rats can be expressed as follows: Y = 0.95X + 19.9 (mm Hg, r = 0.988, 28 degrees C). The new apparatus was also used to confirm the acute hypotensive effects of hydralazine, nifedipine, and pindolol in spontaneously hypertensive rats and the subacute antihypertensive effect of trichlormethiazide in desoxycorticosterone/saline hypertensive rats.