ABSTRACT
This study was designed to investigate the effects an 8-Br-cGMP on the neuronal activity of rat vestibular nuclear cells. Sprague-Dawley rats aged 14 to 16 days were decapitated under ether anesthesia. After treatment with pronase and thermolysin, the dissociated vestibular nuclear cells were transferred into a chamber on an inverted microscope. Spontaneous action potentials and potassium currents were recorded by standard patch-clamp techniques under current and voltage-clamp modes. Twelve vestibular nuclear cells revealed excitatory responses to 1-5 microM of 8-Br-cGMP, and 3 neurons did not respond to 8-Br-cGMP. Whole potassium currents of vestibular nuclear cells were decreased by 8-Br-cGMP (n=12). After calcium-dependent potassium currents were blocked by tetraethylammonium, the potassium currents were not decreased by 8-Br-cGMP. These experimental results suggest that 8-Br-cGMP changes the neuronal activity of vestibular nuclear cells by blocking the calcium-dependent potassium currents that underlie the afterhyperpolarization.
Subject(s)
Aged , Animals , Humans , Rats , Action Potentials , Anesthesia , Ether , Neurons , Nucleotides, Cyclic , Patch-Clamp Techniques , Potassium , Pronase , Rats, Sprague-Dawley , Tetraethylammonium , ThermolysinABSTRACT
This study was designed to investigate the effects an 8-Br-cGMP on the neuronal activity of rat vestibular nuclear cells. Sprague-Dawley rats aged 14 to 16 days were decapitated under ether anesthesia. After treatment with pronase and thermolysin, the dissociated vestibular nuclear cells were transferred into a chamber on an inverted microscope. Spontaneous action potentials and potassium currents were recorded by standard patch-clamp techniques under current and voltage-clamp modes. Twelve vestibular nuclear cells revealed excitatory responses to 1-5 microM of 8-Br-cGMP, and 3 neurons did not respond to 8-Br-cGMP. Whole potassium currents of vestibular nuclear cells were decreased by 8-Br-cGMP (n=12). After calcium-dependent potassium currents were blocked by tetraethylammonium, the potassium currents were not decreased by 8-Br-cGMP. These experimental results suggest that 8-Br-cGMP changes the neuronal activity of vestibular nuclear cells by blocking the calcium-dependent potassium currents that underlie the afterhyperpolarization.
Subject(s)
Aged , Animals , Humans , Rats , Action Potentials , Anesthesia , Ether , Neurons , Nucleotides, Cyclic , Patch-Clamp Techniques , Potassium , Pronase , Rats, Sprague-Dawley , Tetraethylammonium , ThermolysinABSTRACT
Objective To investigate the possible roles of hemodynamics, circulating hormones, cell cation transport and cyclic nucleotides in left ventricular hypertrophy (LVH) of essential hypertension (EH) in vivo. Methods Blood pressure, total peripheral resistance (TPR) and plasma norepinephrine (NE), endothelin (ET), angiotensin Ⅱ (AngⅡ), endogenous digitalis like substances (EDLS) and atrial natriuretic peptide (ANP) were determined, along with the measurements of lymphocytic membrane ion pumps, cations and cyclic nucleotides in 45 EH patients with LVH (12 concentric hypertrophy, 33 eccentric hypertrophy), 30 normal subjects and 45 EH patients without LVH (as double concurrent controls). Multiple stepwise regression analysis was computed using left ventricular mass index (LVMI) as dependent variable and 22 parameters as independent variables. Results (1) In EH patients with LVH, increases were seen in systolic blood pressure, mean arterial pressure (MAP) and NE, ET, AngⅡ, EDLS and ANP as well as lymphocytic Na +, Ca 2+ , cAMP and cAMP/cGMP ratio, while Na + K + ATPase and Ca 2+ ATPase activities, K + and Mg 2+ decreased. (2) Five hormones were related respectively to ion pumps, Na +, Ca 2+ and cyclic nucleotides. (3) LVMI were correlated with NE, ET, AngⅡ and EDLS, Ca 2+ ATPase, Na +, cAMP and cAMP/cGMP ratio. (4) The regression equation revealed that NE, ET, Ca 2+ ATPase, Mg 2+ and cAMP were the independent factors affecting LVH. (5) TPR and AngⅡ were higher, K + was lower in concentric LVH than those in eccentric LVH. Conclusion The changes of hemodynamics, circulating hormones, cell cation transport and cyclic nucleotides, or their interaction may be involved in the pathogenesis of LVH in EH. NE, ET. Ca 2+ ATPase, Mg 2+ and cAMP seem to play more important parts in LVH . TPR , whereas AngⅡ and K + may relate to cocentric LVH.
ABSTRACT
AIM: To detect the role of cyclic nucleotides in the alleviation of hypoxic pulmonary vasoconstriction (HPV) in chronic hypoxic animals. METHODS: The intracellular cAMP and cGMP of the cultured porcine pulmonary arterial smooth muscle cells (PASMC) and endothelial cells (PAEC) were assayed by RIA. The length of single PASMC during acute hypoxia was measured by imaging analysis system. RESULTS: The basal levels of cAMP and cGMP in PASMC and cGMP in PAEC of Chronic hypoxic groups decreased remarkably compared with normoxic groups ( P
ABSTRACT
The levels of cyclic nucleotides(CAMP and CGMP)in the serum and braest tissues of 60 patients with breast cancer or benign breast diseases were measured.It was found that the CAMP level was significantly lower,the CGMP significantly higher and the CAMP/ CGMP ratio was reduced in the serum and breast tissues of the patients with breast cancer.Our findings suggest that CAMP and CGMP might be factors of importance in the origin and development of breast cancer.
ABSTRACT
Plasma levels of artial natriuretic polypeptide (ANP), cyclic GMP (cGMP), renin activity (PRA), angiotensin II (AT II) and arginine vasopressin (AVP) were measured by radioimmunoassay in 30 patients with acute heart failure (AHF), 30 chronic heart failure (CHF), 30 chronic atrial fibrillation (CAF) and 27 paraxysmal atrial fibrillation and supraventricular tachycardia (SVT). The results showed that plasma ANP and cGMP levels in all these four groups were significantly higher than those in the normal group (P