Increase In Atrium Research Articles

Differential <i>β</i><sub>1</sub> Cardiac Adrenoceptor Modulation of Nitric Oxide Isoforms by <i>β</i><sub>1</sub> IgG from Patients with Periodontitis during Short-Term Hypoxia

Background: We demonstrated previously that serum IgG from periodontitis patients interacting with the second extracellular loop of the human cardiac β1 adrenoreceptors triggers the production of second messengers. In this paper we quantified the production of nitrates/nitrites and nitric oxide (NO), which in turn induces nitric oxide synthase (NOS) mRNA expression. Methods: We determined using β1 IgG, NOS activity isoforms, NOS expression, nitrate/nitrite assay, cGMP accumulation and PKC activity. Results: We established that serum β1 IgG autoantibodies and NO might be considered as early markers in normoxia/hypoxia system in rat isolated atria. The β1 IgG autoantibodies from periodontitis patients, while stimulating myocardial atria β1 adrenoreceptors, exert an increase on NO levels indirectly quantified as nitrite/nitrate, which acts as NO-storage molecules with significant increase in neuronal NOS (nNOS) and inducible NOS (iNOS) mRNA levels in hypoxia conditions. The significant increase in nNOS/iNOS mRNA and NOS activity as well as in NO levels after short-time hypoxia in rat isolated atria was detected. The expression of these genes are related with the increase in atria dF/dt, cyclic GMP (cGMP) and protein kinase C (PKC) activity and resemble the results obtained by Isoproterenol, an β1 adrenoreceptor agonist. Conclusion: These findings indicate that short-term hypoxia up-regulated rat atria NO/NOS system in the presence of β1 IgG autoantibodies shows that an antibody interacting with rat atria β1 adrenoreceptor can act as expression inducer of proinflammatory NO and its metabolites and that it might be useful and helps to maintain heart function and to prevent necrosis and subsequent loss of heart function during hypoxia.

Protein kinase C (calcium/phospholipid-dependent protein kinase) in developing chick heart: selective localization to atrium versus ventricle and changes in activity levels during cardiogenesis

Activity levels of calcium/phospholipid-dependent protein kinase were examined in preparations of atria and ventricles from embryonic chick hearts at various stages of development. Activity of protein kinase C was much higher in atria than ventricles. Protein kinase C activity underwent a progressive increase in atria during cardiogenesis, being highest just prior to hatching, followed by a profound decrease in activity after hatching. In contrast, activity of cyclic AMP-dependent protein kinase (protein kinase A), while also higher in atria than ventricles, remained relatively constant at the developmental stages examined, likewise decreasing following hatching. These progressive changes in atrial protein kinase C activity suggest a potential regulatory role for this enzyme in cardiogenesis.

Protein kinase C (calcium/phospholipid-dependent protein kinase) in developing chick heart: selective localization to atrium versus ventricle and changes in a

Activity levels of calcium/phospholipid-dependent protein kinase were examined in preparations of atria and ventricles from embryonic chick hearts at various stages of development. Activity of protein kinase C was much higher in atria than ventricles. Protein kinase C activity underwent a progressive increase in atria during cardiogenesis, being highest just prior to hatching, followed by a profound decrease in activity after hatching. In constrast, activity of cyclic AMP-dependent protein kinase (protein kinase A), while also higher in atria than ventricles, remained relatively constant at the developmental stages examined, likewise decreasing following hatching. These progressive changes in atrial protein kinase C activity suggest a potential regulatory role for this enzyme in cardiogenesis.

EFFECTS OF CHRONIC PROPRANOLOL ADMINISTRATION ON THE FETAL AND NEWBORN RAT

Normal cardiac β-odrenergic function is important for maintenance of an intact stress response in the fetus and neonate,, Propranolol (P), a β-adrebergic blacker is used to treat hypertension, arrhythmias and thyrotoxicosis in pregnancy and appears to cross the placenta. To determine the effects of daily oral P administration on perinatal mortality and growth and cardiac β-receptor function in the fetus and neonate, we administered P in a graded dosage schedule (5-20 mg/kg/day) to 20 Wistar rats on days 7-22 of pregnancy; 19 rats served as controls. 6 (3 controls) were delivered by caesarean section on day 22 for fetal studies. Neonates were studied at 0-12, 24-36, 48-60 hours postpartum. There were no differences (p>0.05) between P and control rats in maternal weight gain, litter size, number of resorption sites and stillbirths, and pup size and heart weight. Cardiac β-receptor function was studied by recording spontaneous rates of impulse initiation of isolated right atrial strips during control superfusion with Tyrode's solution and following superfusion with epinephrine (E), 1 × 10−5M. E induced a significant rate increase in atria from the controls (p<.01). No rate change (P>.05) was seen in atria from fetuses of P-treated mothers. As age increased to 60 hours postpartum the response to E of P-treated neonates increased. By 48-60 hours this did not differ significantly from control .Hence chronic P administration significantly depresses β-responsiveness of fetal & newborn rat hearts which could be potentially dangerous to the fetus in his adaptation to the stresses of labor.