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Although diltiazem has been shown to alleviate vasospastic angina pectoris, its effect on exercise-inducible chronic stable angina has not been objectively studied. Accordingly, the effect of diltiazem was studied in this condition with a placebo controlled double-blind randomized cross-over protocol at three dose levels (120, 180 and 240 mg/day) during graded treadmill exercise. Three end-points were evaluated: 1) time to onset of angina or fatigue if angina were eliminated; 2) time to 1 mm ST segment depression or fatigue if ST depression were eliminated; and 3) time to termination of exercise (2+ angina or fatigue). All end-points were prolonged at all dose levels. At the highest dose of 240 mg/day, time to onset angina or termination was prolonged from a placebo time of 8.0 +/ 0.9 to 9.8 +/- 0.9 minutes (p = < .001); time to ST depression or termination was prolonged from 7.8 +/- 0.9 to 9.1 +/- 0.8 minutes (p = .007); and time to termination was prolonged from 9.9 +/- 0.9 to 10.8 +/- 0.8 minutes (p = .02).

Corneal stromal pH was measured fluorometrically in nine human subjects after 1.5 hours of eye closure while wearing hard gas permeable contact lenses. Six lens types providing a wide range in oxygen transmissibilities (Dk/L)O2 from 0.15 to 55.0 X 10(-9) (cm ml O2/seconds of ml mmHg) were used. Stromal pH upon opening the eyes was directly related to (Dk/L)O2 and ranged from 7.01 to 7.26. These pH values were all significantly lower than the control (no lens), which had a pH of 7.38 (P less than 0.005). After eye opening (lens still on) stromal pH increased and reached a new steady-state (range, 7.11-7.45) in approximately 30 minutes; however, these pH levels were still below the control (no lens) (pH 7.54; P less than 0.005). The rate of pH change after eye opening also increased directly with (Dk/L)O2. The authors conclude that the lenses presently available provide insufficient gas exchange to prevent alteration of corneal pH and suggest that the measurement of stromal pH may provide a sensitive index for evaluating the metabolic effects of contract lens wear.