Age-related effects of platelet activating factor (PAF) in the isolated perfused rat heart.

Platelet Activating Factor (PAF) is a phospholipid that has been implicated as an important mediator of anaphylactic cardiac dysfunction and involved in the toxic effects of the ischaemia-reperfusion process. In the elderly, these phenomena are thought to be exaggerated by the age-related changes in response to several chemical factors and myocardial ischaemia. We evaluated the effects of PAF (acetyl-o-alkyl-l-phosphatidylcholine) on left ventricular systolic (LVSP) and diastolic (LVDP) pressure, coronary flow rate (CFR) and heart rate (HR) in adult (6 months, AH) and senescent (24 months, SH) rat hearts. The perfusion of PAF (10(-8), 10(-7) and 10(-6) M) induced a concentration-related reduction of LVSP, CFR and HR and a linear increase in LVDP. Contractile modifications were more pronounced in senescent hearts: LVSP decreased (P < 0.01) and LVDP increased with respect to younger animals (P < 0.01 vs. AH). This negative inotropic effect was also present in electrically paced hearts. PAF produced conduction arrhythmias ranging from second-degree atrio-ventricular conduction block to cardiac standstill both in adult and senescent hearts; at a higher dose (10(-6) M), cardiac standstill appeared after 96.5 +/- 15.3 s in adult hearts and after 45.5 +/- 17.6 s in senescent hearts (P < 0.01). Lyso-PAF did not modify while specific PAF antagonist compounds CV-3988 inhibited all electromechanical responses both in adult and senescent hearts. These data suggest that age influences the effect of PAF on contractile parameters, coronary flow and conduction arrhythmias by acting on receptors, whose function is unaffected by age.

Age-related effects of ischemia, lidocaine and verapamil on overdrive-induced suppression of ventricular pacemakers in isolated rat heart.

The effect of age on ventricular automaticity in the isolated perfused rat heart was determined under different conditions. When the ventricle is electrically stimulated at a faster rate, drive cessation is followed by a temporary suppression of ventricular automaticity (overdrive suppression). The effects of ischemia, lidocaine and verapamil on overdrive suppression were studied in isolated perfused adult and senescent rat hearts with complete atrio-ventricular block, by monitoring ventricular escape rate and escape rhythm recovery time after 1 minute of overdrive at a constant multiple (x3) of the spontaneous rate. The results demonstrated that: 1) lidocaine decreases ventricular automaticity especially in senescent hearts; 2) verapamil does not modify ventricular automaticity in basal conditions in either adult or senescent hearts; 3) myocardial ischemia causes a reduction in ventricular automaticity and more markedly in senescent hearts; and 4) lidocaine exaggerates the effect of ischemia, while verapamil seems to antagonize its depressant effect more in adult than in senescent hearts.

[Value of electromyography in the study of polyneuropathy caused by industrial glues]. / Importanza dell'elettromiografia nello studio delle polineuropatie da "collanti industriali"

The Authors have studied 47 patients with manufacturing glue neuropathy by electromiography and motor and sensitive nerve conduction velocity recording in medianus, ulnaris and sciatic nerves. The evolution of the disease was studied during two years. From these data, on the basis of recent complete bibliography, the speculated abant the place of damage and the pathogenesis of this professional disease. There was demonstrated the importance of EMG in the earlyer diagnosis and in the medical and legal evaluation of the consequential damages of those diseases.