. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. NEURAL CONTROL OF ARTERIAL VALVES IN HOMAKUS 79 B. 10 mV 15 s Figure 7. The effect of picroloxin (l(r^ M) on UP amplitude dunng train stimulation ( train, ID Hz) of the lateral abdominal arterial valve nerve. (A) Control responses; picrotoxin was added to the bath immedi- ately after this recording. (B) Responses after 20-min exposure to picrotoxin. The bath was Hushed with saline ( inl min"') beginning at 20 min. (C) Recording after 10 min of saline wash. (Dl UP ampliaide had partially recovered after 20 min of
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. NEURAL CONTROL OF ARTERIAL VALVES IN HOMAKUS 79 B. 10 mV 15 s Figure 7. The effect of picroloxin (l(r^ M) on UP amplitude dunng train stimulation ( train, ID Hz) of the lateral abdominal arterial valve nerve. (A) Control responses; picrotoxin was added to the bath immedi- ately after this recording. (B) Responses after 20-min exposure to picrotoxin. The bath was Hushed with saline ( inl min"') beginning at 20 min. (C) Recording after 10 min of saline wash. (Dl UP ampliaide had partially recovered after 20 min of washing. The vertical lines on each trace are stimulus artifacts. The nature of the innervation of the other cardioarterial valves in not known for lobsters. In the isopod B. doeder- leini. Kihara et al. (1985) found that some cardioarterial valves are dually and antagonistically innervated, whereas others receive only excitatory or inhibitory innervation. It seems reasonable to assume that the complexity of the innervation of a valve is related to the degree of control required of that valve, and of the overall architec- ture of the arterial system of which the valve is a part. For example, the sternal artery in H. americamis supplies a number of critical structures, including the mouthparts, scaphognathites, walking legs, gut, and ventral nerve cord. It is unlikely that completely stopping hemolymph flow into this artery would ever be desirable, which may help explain the absence of excitatory nervous control of this valve. Flow into the sternal artery would, however, be indirectly reduced if the cardioarterial valves of other arteries and LAAVs were to dilate, lowering the relative flow resistances of other arterial pathways out of the heart. On the other hand, the DAA supplies two different vascu- lar beds, and the complex control that includes both excit- atory and inhibitory innervation would allow redistribu- tion between them. We presuine that the neural control of the
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