Diabetes mellitus differently affects electrical membrane properties of vagal afferent neurons of rats

Figures

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  FIGURE 1. Representative traces of action potential (AP) of A0, Ainf, and Cinf nodose ganglia neuronal groups. The top black lines represent AP's and bottom red and blue lines show 1st (dV/dt) and 2nd (d2V/dt2) derivatives of AP signal. Vertical gray lines crossing AP and derivatives signals represent the time at which dV/dt and d2V/dt2 are equal to zero and are also indicated by small letters for 1st derivative (a and b for all neuronal groups) and 2nd derivative signal (c and d for all neuronal groups and e and d' for Ainf neurons). The broken horizontal line represents 0.0 voltage of dV/dt signal. The calibration bar is related to the AP waveform.

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  FIGURE 2. Representative traces recorded in A0, Ainf, and Cinf neurons from nodose ganglia of control and diabetic rats. The upper traces represent A0 neurons, the middle traces (panels c and d) represent Ainf neurons, and the lower traces (panels e and f) represent Cinf neurons. The inserts show the first derivative of action potential that was used to classify the groups. The calibration bar is related to action potential traces.

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  FIGURE 3. Alterations produced by diabetes mellitus on passive electrical membrane properties of nodose ganglia neuronal groups. CT, control; DB, diabetic; RMP, resting membrane potential; Rin, input resistance; A0, Ainf, and Cinf, represent the three types of neurons, according to dV/dt of an action potential. Data are expressed as mean ± S.E.M and the number of cells is shown inside the bars. *p < 0.05, when compared to the control group (Student t‐test).

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  FIGURE 4. Alterations produced by diabetes mellitus on active electrical membrane properties of nodose ganglia neuronal groups. CT, control; DB, diabetic; A0, Ainf, and Cinf, the three types of neurons, were classified according to dV/dt of an action potential (AP). Data are expressed as mean ± S.E.M and the number of cells is shown inside the bars. *p < 0.05, when compared to the control group (Student t‐test).

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  FIGURE 5. Alterations produced by diabetes mellitus on after‐hyperpolarization (AHP) parameters of nodose ganglia neuronal groups. CT, control; DB, diabetic; A0, Ainf, and Cinf, the three types of neurons, according to dV/dt of an action potential. Data are expressed as mean ± S.E.M and the number of cells is shown inside the bars. *p < 0.05, when compared to the control group (Student t‐test).

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  FIGURE 6. Alterations produced by diabetes mellitus on Na+ currents of dissociated nodose ganglion neurons. Panel a shows representative recordings of Na+ current activation in control (left), DB1 (center), and DB2 (right) groups. Panel b shows the Na+ current inactivation representative traces in the same groups. Insets in panels a and b show the voltage protocols used. Panel c is shown the frequency distribution of the peak INa of Control c1 and of Diabetic groups c2 DB1 and DB2. Panel d shows Current x Voltage relationship for INa activation. The Na+ current, normalized by its maximum value, at different potentials for activation and inactivation protocols, are shown in panels e and f, respectively. Small letters in panels d, e, and f indicate a statistical difference between DB2 versus control (a) and DB1 groups (b) (p < 0.05, ANOVA followed by Holm‐Sidak test). The number of neurons tested was 30, 10, and 31 for control, DB1 and DB2, respectively.