Relationship between abnormal regulation of cytoplasmic calcium and elevated blood pressure in patients with primary hyperparathyroidism.

Primary hyperparathyroidism (HPT) is characterised by a defective calcium sensitivity of the parathyroid glands. HPT is, furthermore, associated with a high prevalence of hypertension. In the present study BP was measured before operation, during surgery and after operation in 42 HPT patients and in 15 control subjects operated for non-toxic goitre. Parathyroid tissue was removed from all patients and the concentration of cytoplasmic calcium [Ca2+]i was determined in vitro in dispersed single cells by means of microfluometry at extracellular calcium concentrations of 0.5 mM and 3.0 mM. The SBP levels were found to be raised both before (158 +/- 23 (SD) mmHg vs. 144 +/- 24 mmHg in controls, P < 0.05), during surgery (maximal level 167 +/- 22 mmHg vs. 146 +/- 16 mmHg in controls, P < 0.01) and after operation (maximal level 180 +/- 26 mmHg vs. 148 +/- 20 mmHg in controls, P < 0.001) in the HPT subject when compared with controls. SBP during surgery was found to be related to the in vitro measured [Ca2+]i in the parathyroid cells at 3.0 mM extracellular calcium concentration or to the ratio of [Ca2+]i at 3.0 mM-0.5 mM (r = -0.25 and -0.27, respectively; P < 0.05). The degree of suppression of PTH release in vitro at 3.0 mM extracellular calcium was found to be related to both systolic and diastolic BP (r = 0.57 and r = 0.53, respectively; P < 0.05) before surgery. In conclusion, BP was found to be raised in HPT patients both before operation as well as during surgery and after operation.(ABSTRACT TRUNCATED AT 250 WORDS)