In vitro effect of nicotine on red blood cell deformability in untreated and treated essential hypertension.

The in vitro effect of nicotine (10(-7) mol l-1) on red blood cell (RBC) deformability in essential hypertension, efficacy of antihypertensive treatment (with the combination of enalapril, nifedipine and indapamid) on hypertension-induced decrease in RBC deformability and interaction between nicotine and efficacy of antihypertensive treatment were investigated in the blood samples obtained from 16 patients with untreated hypertension (UH) and 18 patients with treated hypertension (TH). Fourteen healthy subjects served as normotensive (NT) group. RBC deformability was assessed by using a gravity-driven microfiltration technique. In the UH group, the RBC deformability was found to be significantly lower than those in NT (0.623 +/- 0.06 versus 0.753 +/- 0.078, p < 0.001) and in TH (0.623 +/- 0.06 versus 0.732 +/- 0.055, p < 0.001) groups. The RBC deformability in the TH group was not significantly different than that in the NT group (0.753 +/- 0.078 versus 0.732 +/- 0.055, p > 0.05). Nicotine, in vitro, decreased deformability in the NT (0.668 +/- 0.067 versus 0.753 +/- 0.078, p > 0.0001), UH (0.509 +/- 0.052 versus 0.623 +/- 0.06, p < 0.0001) and TH (0.651 +/- 0.046 versus 0.732 +/- 0.055, p < 0.001) groups. The effect on the UH group was significantly greater than those in the NT (p < 0.0001) and TH (p < 0.0001) groups. These results suggest that nicotine and hypertension independently and cumulatively decrease the RBC deformability and nicotine inhibits the efficacy of antihypertensive treatment on RBC deformability.

Effect of acute smoking on red blood cell deformability in healthy young and elderly non-smokers, and effect of verapamil on age- and acute smoking-induced change in red blood cell deformability.

The effects of age and acute smoking on red blood cell (RBC) deformability in non-smokers have been studied. RBC ATP levels and in vitro effects of verapamil on pre- and post-smoking filterabilities have been determined in an attempt to make an approach to the mechanism(s) responsible for the effect of age and acute smoking on RBC deformability. Nine young and nine elderly healthy non-smokers volunteered to the study. Venous blood samples obtained before and after the smoking of one cigarette, were used for ATP analysis and RBC deformability determination. ATP was determined enzymatically, deformability was assessed by gravity driven microfiltration technique. Verapamil was added to pre- and post-smoking blood samples to yield a final concentration of 1 mg-1. RBC deformability was found to decrease in the elderly group by 19.1% of that of the young group (p < 0.001). Acute smoking decreased the filterabilities of RBCs by 15.3% (p < 0.0001) and 15.9% (p < 0.001) of their pre-smoking values in the young and the elderly groups respectively. The smoking-induced decreases in RBC deformability were found to be associated with slight but significant decreases (p < 0.02 and p < 0.005 for the young and the elderly group respectively) in RBC ATP concentrations. Ca2+ channel blockade with verapamil did not produce any significant change in pre- and post-smoking filterabilities of RBCs from the young group, but improved these variables by 9.7% (p < 0.005) and 10.7% (p < 0.05) in the elderly group. In conclusion age and smoking are two independent factors that affect the deformability of human RBCs.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction between beta-blockers and contrast media during intracoronary administration in rabbit heart.

The effects of ionic, meglumine sodium diatrizoate (Urografin 76) and nonionic, iohexol contrast media were examined in the absence and presence of propranolol, a beta-blocker having nonspecific membrane stabilizing action and atenolol, a beta-blocker lacking nonspecific membrane stabilizing action on Langendorff-perfused rabbit hearts. Contrast medium, 0.7 ml, was injected into the aortic root in the absence and presence of 10(-7) and 10(-5) M beta-blocker to observe the changes in resting tension, force of contraction, rate of contraction, heart rate and PR interval. Beta-blockers and contrast media interact in affecting myocardial contractility, heart rate and atrioventricular conduction. The interaction is milder when the beta-blocker lacks membrane stabilizing activity and the contrast medium is nonionic.