Parasympathetic cardiac ganglions

Peripheral Gl, vascular and bronchial smooth muscle, vascular endothelium, platelets Peripheral Smooth muscle of ileum, stomach fundus (rat), uterus, vasculature, endothelium Peripheral None identified Peripheral Post-ganglionic sympathetic neurons, sensory neurons Peripheral Cardiac muscle, post-ganglionic parasympathetic neurons (myenteric plexus), esophageal and vascular smooth muscle... 

The actions of anticholinesterase agents on the cardiovascular system are complex. The primary effect produced by potentiation of vagal stimulation is bradycardia with a consequent decrease in cardiac output and blood pressure. However, potentiation of both parasympathetic and sympathetic ganglionic transmis-... 

E. The effect of ganglionic blockade depends upon the predominant autonomic tone exerted within various organ systems. Since the activity of the parasympathetic nervous system predominates in the eye, the effect of ganglionic blockade is mydriasis, not miosis. Similarly, stimulation of the genital tract and urinary retention would be decreased. Since sympathetic nervous system activity predominates in blood vessels and the ventricles, vasodilation and a decreased cardiac output would follow ganglionic blockade. 

The basis for the antihypertensive activity of the ganglionic blockers lies in their ability to block transmission through autonomic ganglia (Fig. 20.2C). This action, which results in a decrease in the number of impulses passing down the postganglionic sympathetic (and parasympathetic) nerves, decreases vascular tone, cardiac output, and blood pressure. These drugs prevent the interaction of acetylcholine (the transmitter of the preganglionic autonomic nerves) with the nicotinic receptors on postsynaptic neuronal membranes of both the sympathetic and parasympathetic nervous systems. 

Trimethaphan camsylate is a ganglionic-blocking drug that inhibits both sympathetic and parasympathetic autonomic activities. It has a rapid onset and brief duration of action and must be admiifistered by continuous intravenous infusion with constant monitoring of blood pressure. Trimethaphan camsylate is particularly useful in aortic dissection because it can be titrated carefully to permit smooth control of blood pressure and because it decreases cardiac output and left ventricular ejection rate. Tachyphylaxis... 

The absence of parallelism between the blocking effect upon the sympathetic (superior cervical ganglion) and parasympathetic ganglia (those of the vagal cardiac branches) is worthy of note (Table 11). 

The mechanism of these blood pressure and other cardiovascular effects has been the subject for much study. Reduction in blood pressure in anesthesized dogs caused by administration of 2.5 mg/kg i.v. of A -THC is accompanied by a decrease in cardiac output and an increase in local vascular resistance. The fractional blood flow to the vital coronary, cerebral and renal beds was unchanged The reduction in cardiac output appears to result from the action of A -THC on the heart rate (bradycardia) as well as venous return. A maximal degree of bradycardia is produced only when both sympathetic and parasympathetic innervation of the heart is intact. A -THC appears to be devoid of any ganglionic or 8-... 

---