Cerebral blood flow was measured both under conditions of normocapnia and hypercapnia in 22 diabetic patients and 20 normal control subjects, using either the intravenous 133Xe method or the closely comparable 133Xe inhalation method. While 19 out of 20 control subjects responded appropriately to hypercapnia with an increase in flow, eight of the diabetic patients failed to respond normally, this difference being significant (p = 0.03). Those manifesting an abnormal response included young, insulin-dependent patients with a short duration of diabetes and no clinical evidence of complications.

Propranolol and Dyazide (25 mg hydrochlorothiazide and 50 mg triamterene) were used singly to reduce the elevated blood pressure (systolic ranging from 170 to 271 mmHg and diastolic ranging from 100 to 141 mmHg) of 38 elderly hypertensive patients whose ages ranged from 69 to 91 years. Each compound was administered for a period of four weeks with a wash-out period of four weeks in between. The following parameters were assessed before and after each treatment period: cerebral blood flow (CBF), mental functions, cardiac output (CO), electrocardiogram, glomerular filtration rate (GFR) and serum biochemistry. Both systolic and diastolic blood pressure were significantly reduced following the administration of either compound. No significant change in CBF and CO could be observed after reducing the blood pressure whether Propranolol or Dyazide was used. The GFR was, however, significantly reduced and the plasma creatinine significantly increased following Dyazide but not Propranolol administration. As expected the administration of the latter compound was associated with a significant bradycardia. No significant change could be observed in the other parameters studied.