Relationships between eruptive force and blood pressure, and colloid osmotic pressure

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1. Arterial blood pressure was measured in unanaesthetized rats using a hemadynamometer (UR-5000, UEDA). The systolic, diastolic and mean blood pressures were 156(〕SY.+-.〔)9, 109(〕SY.+-.〔)6 and 124(〕SY.+-.〔)7 mmHg respectively. the eruption rate of the rat incisor decreased to 83% of the control value under urethane anaesthesia. 2. colloid osmotic pressure in the tissue fluid within the incisor pulp ranged from 5.0-14.3 mmHg which was lower than that in the serum (17 mmHg). Intravenous injection of hypertonic dextran solution (20-30%) did not affect the eruption rate. 3. The eruption rates were 550(〕SY.+-.〔)127 mum/24 h and 548(〕SY.+-.〔)137 mum/24 h under urethane and halothane anaesthesia respectively. The mean blood pressures were also measured directly from the mid-tail artery which were 77(〕SY.+-.〔)16mmHg and 78(〕SY.+-.〔)12 mmHg under urethane and halothane anaesthesia respectively. A significant correlation was found between the eruption rate and the mean blood pressure. 4. Effects of adrenergic drugs on the mean blood pressure, the eruption rate and the eruptive force were examined.Temporal increase of the mean blood pressure in accord with increases in the eruption rate and eruptive force was observed after intravenous injection of adrenaline or noradrenaline. A decrease of the mean blood pressure and marked reductions of the eruption rate and eruptive force were observed following intravenous injection of adrenaline or isoproterenol. Reductions of the eruption rate and eruptive force and their recovery processes were not associated with changes in the mean blood pressure. 5. It is suggested that there are close relations between the systemic arterial blood pressures and the eruption rates and eruptive forces of the rat incisor, although the time course and quantity of these changes are not always parallel with each other.